No More Learning

There is another kind of ines or fibre that is found in
blood, but not in the blood of all animals alike. If this fibre be
left in the blood, the blood will coagulate; if it be removed or
extracted, the blood is found to be incapable of coagulation. While,
however, this fibrous matter is found in the blood of the great
majority of animals, it is not found in all. For instance, we fail
to find it in the blood of the deer, the roe, the antelope, and some
other animals; and, owing to this deficiency of the fibrous tissue,
the blood of these animals does not coagulate to the extent observed
in the blood of other animals. The blood of the deer coagulates to
about the same extent as that of the hare: that is to the blood in
either case coagulates, but not into a stiff or jelly-like
substance, like the blood of ordinary animals, but only into a flaccid
consistency like that of milk which is not subjected to the action
of rennet. The blood of the antelope admits of a firmer consistency in
coagulation; for in this respect it resembles, or only comes a
little short of, the blood of sheep. Such are the properties of
vein, sinew, and fibrous tissue.

7

The bones in animals are all connected with one single bone, and
are interconnected, like the veins, in one unbroken sequence; and
there is no instance of a bone standing apart by itself. In all
animals furnished with bones, the spine or backbone is the point of
origin for the entire osseous system. The spine is composed of
vertebrae, and it extends from the head down to the loins. The
vertebrae are all perforated, and, above, the bony portion of the head
is connected with the topmost vertebrae, and is designated the
'skull'. And the serrated lines on the skull are termed 'sutures'.

The skull is not formed alike in all animals. In some animals
the skull consists of one single undivided bone, as in the case of the
dog; in others it is composite in structure, as in man; and in the
human species the suture is circular in the female, while in the
male it is made up of three separate sutures, uniting above in
three-corner fashion; and instances have been known of a man's skull
being devoid of suture altogether. The skull is composed not of four
bones, but of six; two of these are in the region of the ears, small
in comparison with the other four. From the skull extend the jaws,
constituted of bone. (Animals in general move the lower jaw; the river
crocodile is the only animal that moves the upper one. ) In the jaws is
the tooth-system; and the teeth are constituted of bone, and are
half-way perforated; and the bone in question is the only kind of bone
which it is found impossible to grave with a graving tool.

On the upper part of the course of the backbone are the
collar-bones and the ribs. The chest rests on ribs; and these ribs
meet together, whereas the others do not; for no animal has bone in
the region of the stomach. Then come the shoulder-bones, or
blade-bones, and the arm-bones connected with these, and the bones
in the hands connected with the bones of the arms. With animals that
have forelegs, the osseous system of the foreleg resembles that of the
arm in man.

Below the level of the backbone, after the haunch-bone, comes
the hip-socket; then the leg-bones, those in the thighs and those in
the shins, which are termed colenes or limb-bones, a part of which
is the ankle, while a part of the same is the so-called 'plectrum'
in those creatures that have an ankle; and connected with these
bones are the bones in the feet.

Now, with all animals that are supplied with blood and furnished
with feet, and are at the same time viviparous, the bones do not
differ greatly one from another, but only in the way of relative
hardness, softness, or magnitude. A further difference, by the way, is
that in one and the same animal certain bones are supplied with
marrow, while others are destitute of it. Some animals might on casual
observation appear to have no marrow whatsoever in their bones: as
is the case with the lion, owing to his having marrow only in small
amount, poor and thin, and in very few bones; for marrow is found in
his thigh and armbones. The bones of the lion are exceptionally
hard; so hard, in fact, that if they are rubbed hard against one
another they emit sparks like flint-stones. The dolphin has bones, and
not fish-spine.

Of the other animals supplied with blood, some differ but
little, as is the case with birds; others have systems analogous, as
fishes; for viviparous fishes, such as the cartilaginous species,
are gristle-spined, while the ovipara have a spine which corresponds
to the backbone in quadrupeds. This exceptional property has been
observed in fishes, that in some of them there are found delicate
spines scattered here and there throughout the fleshy parts. The
serpent is similarly constructed to the fish; in other words, his
backbone is spinous. With oviparous quadrupeds, the skeleton of the
larger ones is more or less osseous; of the smaller ones, more or less
spinous. But all sanguineous animals have a backbone of either one
kind or other: that is, composed either of bone or of spine.

The other portions of the skeleton are found in some animals and
not found in others, but the presence or the absence of this and
that part carries with it, as a matter of course, the presence or
the absence of the bones or the spines corresponding to this or that
part. For animals that are destitute of arms and legs cannot be
furnished with limb-bones: and in like manner with animals that have
the same parts, but yet have them unlike in form; for in these animals
the corresponding bones differ from one another in the way of relative
excess or relative defect, or in the way of analogy taking the place
of identity. So much for the osseous or spinous systems in animals.

8

Gristle is of the same nature as bone, but differs from it in
the way of relative excess or relative defect. And just like bone,
cartilage also, if cut, does not grow again. In terrestrial viviparous
sanguinea the gristle formations are unperforated, and there is no
marrow in them as there is in bones; in the selachia, however--for, be
it observed, they are gristle-spined--there is found in the case of
the flat space in the region of the backbone, a gristle-like substance
analogous to bone, and in this gristle-like substance there is a
liquid resembling marrow. In viviparous animals furnished with feet,
gristle formations are found in the region of the ears, in the
nostrils, and around certain extremities of the bones.

9

Furthermore, there are parts of other kinds, neither identical
with, nor altogether diverse from, the parts above enumerated: such as
nails, hooves, claws, and horns; and also, by the way, beaks, such
as birds are furnished with-all in the several animals that are
furnished therewithal. All these parts are flexible and fissile; but
bone is neither flexible nor fissile, but frangible.

And the colours of horns and nails and claw and hoof follow the
colour of the skin and the hair. For according as the skin of an
animal is black, or white, or of medium hue, so are the horns, the
claws, or the hooves, as the case may be, of hue to match. And it is
the same with nails. The teeth, however, follow after the bones.
Thus in black men, such as the Aethiopians and the like, the teeth and
bones are white, but the nails are black, like the whole of the skin.

Horns in general are hollow at their point of attachment to the
bone which juts out from the head inside the horn, but they have a
solid portion at the tip, and they are simple and undivided in
structure. In the case of the stag alone of all animals the horns
are solid throughout, and ramify into branches (or antlers). And,
whereas no other animal is known to shed its horns, the deer sheds its
horns annually, unless it has been castrated; and with regard to the
effects of castration in animals we shall have much to say
hereafter. Horns attach rather to the skin than to the bone; which
will account for the fact that there are found in Phrygia and
elsewhere cattle that can move their horns as freely as their ears.

Of animals furnished with nails-and, by the way, all animals
have nails that have toes, and toes that have feet, except the
elephant; and the elephant has toes undivided and slightly
articulated, but has no nails whatsoever--of animals furnished with
nails, some are straight-nailed, like man; others are crooked
nailed, as the lion among animals that walk, and the eagle among
animals that fly.

10

The following are the properties of hair and of parts analogous to
hair, and of skin or hide. All viviparous animals furnished with
feet have hair; all oviparous animals furnished with feet have
horn-like tessellates; fishes, and fishes only, have scales-that is,
such oviparous fishes as have the crumbling egg or roe. For of the
lanky fishes, the conger has no such egg, nor the muraena, and the eel
has no egg at all.

The hair differs in the way of thickness and fineness, and of
length, according to the locality of the part in which it is found,
and according to the quality of skin or hide on which it grows. For,
as a general rule, the thicker the hide, the harder and the thicker is
the hair; and the hair is inclined to grow in abundance and to a great
length in localities of the bodies hollow and moist, if the localities
be fitted for the growth of hair at all. The facts are similar in
the case of animals whether coated with scales or with tessellates.
With soft-haired animals the hair gets harder with good feeding, and
with hard-haired or bristly animals it gets softer and scantier from
the same cause. Hair differs in quality also according to the relative
heat or warmth of the locality: just as the hair in man is hard in
warm places and soft in cold ones. Again, straight hair is inclined to
be soft, and curly hair to be bristly.

11

Hair is naturally fissile, and in this respect it differs in
degree in diverse animals. In some animals the hair goes on
gradually hardening into bristle until it no longer resembles hair but
spine, as in the case of the hedgehog. And in like manner with the
nails; for in some animals the nail differs as regards solidity in
no way from bone.

Of all animals man has the most delicate skin: that is, if we take
into consideration his relative size. In the skin or hide of all
animals there is a mucous liquid, scanty in some animals and plentiful
in others, as, for instance, in the hide of the ox; for men
manufacture glue out of it. (And, by the way, in some cases glue is
manufactured from fishes also. ) The skin, when cut, is in itself
devoid of sensation; and this is especially the case with the skin
on the head, owing to there being no flesh between it and the skull.
And wherever the skin is quite by itself, if it be cut asunder, it
does not grow together again, as is seen in the thin part of the
jaw, in the prepuce, and the eyelid. In all animals the skin is one of
the parts that extends continuous and unbroken, and it comes to a stop
only where the natural ducts pour out their contents, and at the mouth
and nails.

All sanguineous animals, then, have skin; but not all such animals
have hair, save only under the circumstances described above. The hair
changes its colour as animals grow old, and in man it turns white or
grey. With animals, in general, the change takes place, but not very
obviously, or not so obviously as in the case of the horse. Hair turns
grey from the point backwards to the roots. But, in the majority of
cases, grey hairs are white from the beginning; and this is a proof
that greyness of hair does not, as some believe to be the case,
imply withering or decrepitude, for no part is brought into
existence in a withered or decrepit condition.

In the eruptive malady called the white-sickness all the hairs get
grey; and instances have been known where the hair became grey while
the patients were ill of the malady, whereas the grey hairs shed off
and black ones replaced them on their recovery. (Hair is more apt to
turn grey when it is kept covered than when exposed to the action of
the outer air. ) In men, the hair over the temples is the first to turn
grey, and the hair in the front grows grey sooner than the hair at the
back; and the hair on the pubes is the last to change colour.

Some hairs are congenital, others grow after the maturity of the
animal; but this occurs in man only. The congenital hairs are on the
head, the eyelids, and the eyebrows; of the later growths the hairs on
the pubes are the first to come, then those under the armpits, and,
thirdly, those on the chin; for, singularly enough, the regions
where congenital growths and the subsequent growths are found are
equal in number. The hair on the head grows scanty and sheds out to
a greater extent and sooner than all the rest. But this remark applies
only to hair in front; for no man ever gets bald at the back of his
head. Smoothness on the top of the head is termed 'baldness', but
smoothness on the eyebrows is denoted by a special term which means
'forehead-baldness'; and neither of these conditions of baldness
supervenes in a man until he shall have come under the influence of
sexual passion. For no boy ever gets bald, no woman, and no
castrated man. In fact, if a man be castrated before reaching puberty,
the later growths of hair never come at all; and, if the operation
take place subsequently, the aftergrowths, and these only, shed off;
or, rather, two of the growths shed off, but not that on the pubes.

Women do not grow hairs on the chin; except that a scanty beard
grows on some women after the monthly courses have stopped; and
similar phenomenon is observed at times in priestesses in Caria, but
these cases are looked upon as portentous with regard to coming
events. The other after-growths are found in women, but more scanty
and sparse. Men and women are at times born constitutionally and
congenitally incapable of the after-growths; and individuals that
are destitute even of the growth upon the pubes are constitutionally
impotent.

Hair as a rule grows more or less in length as the wearer grows in
age; chiefly the hair on the head, then that in the beard, and fine
hair grows longest of all. With some people as they grow old the
eyebrows grow thicker, to such an extent that they have to be cut off;
and this growth is owing to the fact that the eyebrows are situated at
a conjuncture of bones, and these bones, as age comes on, draw apart
and exude a gradual increase of moisture or rheum. The eyelashes do
not grow in size, but they shed when the wearer comes first under
the influence of sexual feelings, and shed all the quicker as this
influence is the more powerful; and these are the last hairs to grow
grey.

Hairs if plucked out before maturity grow again; but they do not
grow again if plucked out afterwards. Every hair is supplied with a
mucous moisture at its root, and immediately after being plucked out
it can lift light articles if it touch them with this mucus.

Animals that admit of diversity of colour in the hair admit of a
similar diversity to start with in the skin and in the cuticle of
the tongue.

In some cases among men the upper lip and the chin is thickly
covered with hair, and in other cases these parts are smooth and the
cheeks are hairy; and, by the way, smooth-chinned men are less
inclined than bearded men to baldness.

The hair is inclined to grow in certain diseases, especially in
consumption, and in old age, and after death; and under these
circumstances the hair hardens concomitantly with its growth, and
the same duplicate phenomenon is observable in respect of the nails.

In the case of men of strong sexual passions the congenital
hairs shed the sooner, while the hairs of the after-growths are the
quicker to come. When men are afflicted with varicose veins they are
less inclined to take on baldness; and if they be bald when they
become thus afflicted, they have a tendency to get their hair again.

If a hair be cut, it does not grow at the point of section; but it
gets longer by growing upward from below. In fishes the scales grow
harder and thicker with age, and when the amimal gets emaciated or
is growing old the scales grow harder. In quadrupeds as they grow
old the hair in some and the wool in others gets deeper but scantier
in amount: and the hooves or claws get larger in size; and the same is
the case with the beaks of birds. The claws also increase in size,
as do also the nails.

12

With regard to winged animals, such as birds, no creature is
liable to change of colour by reason of age, excepting the crane.
The wings of this bird are ash-coloured at first, but as it grows
old the wings get black. Again, owing to special climatic
influences, as when unusual frost prevails, a change is sometimes
observed to take place in birds whose plumage is of one uniform
colour; thus, birds that have dusky or downright black plumage turn
white or grey, as the raven, the sparrow, and the swallow; but no case
has ever yet been known of a change of colour from white to black.
(Further, most birds change the colour of their plumage at different
seasons of the year, so much so that a man ignorant of their habits
might be mistaken as to their identity. ) Some animals change the
colour of their hair with a change in their drinking-water, for in
some countries the same species of animal is found white in one
district and black in another. And in regard to the commerce of the
sexes, water in many places is of such peculiar quality that rams,
if they have intercourse with the female after drinking it, beget
black lambs, as is the case with the water of the Psychrus
(so-called from its coldness), a river in the district of Assyritis in
the Chalcidic Peninsula, on the coast of Thrace; and in Antandria
there are two rivers of which one makes the lambs white and the
other black. The river Scamander also has the reputation of making
lambs yellow, and that is the reason, they say, why Homer designates
it the 'Yellow River. ' Animals as a general rule have no hair on their
internal surfaces, and, in regard to their extremities, they have hair
on the upper, but not on the lower side.

The hare, or dasypod, is the only animal known to have hair inside
its mouth and underneath its feet. Further, the so-called mousewhale
instead of teeth has hairs in its mouth resembling pigs' bristles.

Hairs after being cut grow at the bottom but not at the top; if
feathers be cut off, they grow neither at top nor bottom, but shed and
fall out. Further, the bee's wing will not grow again after being
plucked off, nor will the wing of any creature that has undivided
wings. Neither will the sting grow again if the bee lose it, but the
creature will die of the loss.

13

In all sanguineous animals membranes are found. And membrane
resembles a thin close-textured skin, but its qualities are different,
as it admits neither of cleavage nor of extension. Membrane envelops
each one of the bones and each one of the viscera, both in the
larger and the smaller animals; though in the smaller animals the
membranes are indiscernible from their extreme tenuity and minuteness.
The largest of all the membranes are the two that surround the
brain, and of these two the one that lines the bony skull is
stronger and thicker than the one that envelops the brain; next in
order of magnitude comes the membrane that encloses the heart. If
membrane be bared and cut asunder it will not grow together again, and
the bone thus stripped of its membrane mortifies.

14

The omentum or caul, by the way, is membrane. All sanguineous
animals are furnished with this organ; but in some animals the organ
is supplied with fat, and in others it is devoid of it. The omentum
has both its starting-point and its attachment, with ambidental
vivipara, in the centre of the stomach, where the stomach has a kind
of suture; in non-ambidental vivipara it has its starting-point and
attachment in the chief of the ruminating stomachs.

15

The bladder also is of the nature of membrane, but of membrane
peculiar in kind, for it is extensile. The organ is not common to
all animals, but, while it is found in all the vivipara, the
tortoise is the only oviparous animal that is furnished therewithal.
The bladder, like ordinary membrane, if cut asunder will not grow
together again, unless the section be just at the commencement of
the urethra: except indeed in very rare cases, for instances of
healing have been known to occur. After death, the organ passes no
liquid excretion; but in life, in addition to the normal liquid
excretion, it passes at times dry excretion also, which turns into
stones in the case of sufferers from that malady. Indeed, instances
have been known of concretions in the bladder so shaped as closely
to resemble cockleshells.

Such are the properties, then, of vein, sinew and skin, of fibre
and membrane, of hair, nail, claw and hoof, of horns, of teeth, of
beak, of gristle, of bones, and of parts that are analogous to any
of the parts here enumerated.

16

Flesh, and that which is by nature akin to it in sanguineous
animals, is in all cases situated in between the skin and the bone, or
the substance analogous to bone; for just as spine is a counterpart of
bone, so is the flesh-like substance of animals that are constructed a
spinous system the counterpart of the flesh of animals constructed
on an osseous one.

Flesh can be divided asunder in any direction, not lengthwise only
as is the case with sinew and vein. When animals are subjected to
emaciation the flesh disappears, and the creatures become a mass of
veins and fibres; when they are over fed, fat takes the place of
flesh. Where the flesh is abundant in an animal, its veins are
somewhat small and the blood abnormally red; the viscera also and
the stomach are diminutive; whereas with animals whose veins are large
the blood is somewhat black, the viscera and the stomach are large,
and the flesh is somewhat scanty. And animals with small stomachs
are disposed to take on flesh.

17

Again, fat and suet differ from one another. Suet is frangible
in all directions and congeals if subjected to extreme cold, whereas
fat can melt but cannot freeze or congeal; and soups made of the flesh
of animals supplied with fat do not congeal or coagulate, as is
found with horse-flesh and pork; but soups made from the flesh of
animals supplied with suet do coagulate, as is seen with mutton and
goat's flesh. Further, fat and suet differ as to their localities: for
fat is found between the skin and flesh, but suet is found only at the
limit of the fleshy parts. Also, in animals supplied with fat the
omentum or caul is supplied with fat, and it is supplied with suet
in animals supplied with suet. Moreover, ambidental animals are
supplied with fat, and non-ambidentals with suet.

Of the viscera the liver in some animals becomes fatty, as,
among fishes, is the case with the selachia, by the melting of whose
livers an oil is manufactured. These cartilaginous fish themselves
have no free fat at all in connexion with the flesh or with the
stomach. The suet in fish is fatty, and does not solidify or
congeal. All animals are furnished with fat, either intermingled
with their flesh, or apart. Such as have no free or separate fat are
less fat than others in stomach and omentum, as the eel; for it has
only a scanty supply of suet about the omentum. Most animals take on
fat in the belly, especially such animals as are little in motion.

The brains of animals supplied with fat are oily, as in the pig;
of animals supplied with suet, parched and dry. But it is about the
kidneys more than any other viscera that animals are inclined to
take on fat; and the right kidney is always less supplied with fat
than the left kidney, and, be the two kidneys ever so fat, there is
always a space devoid of fat in between the two. Animals supplied with
suet are specially apt to have it about the kidneys, and especially
the sheep; for this animal is apt to die from its kidneys being
entirely enveloped. Fat or suet about the kidney is superinduced by
overfeeding, as is found at Leontini in Sicily; and consequently in
this district they defer driving out sheep to pasture until the day is
well on, with the view of limiting their food by curtailment of the
hours of pasture.

18

The part around the pupil of the eye is fatty in all animals,
and this part resembles suet in all animals that possess such a part
and that are not furnished with hard eyes.

Fat animals, whether male or female, are more or less unfitted for
breeding purposes. Animals are disposed to take on fat more when old
than when young, and especially when they have attained their full
breadth and their full length and are beginning to grow depthways.

19

And now to proceed to the consideration of the blood. In
sanguineous animals blood is the most universal and the most
indispensable part; and it is not an acquired or adventitious part,
but it is a consubstantial part of all animals that are not corrupt or
moribund. All blood is contained in a vascular system, to wit, the
veins, and is found nowhere else, excepting in the heart. Blood is not
sensitive to touch in any animal, any more than the excretions of
the stomach; and the case is similar with the brain and the marrow.
When flesh is lacerated, blood exudes, if the animal be alive and
unless the flesh be gangrened. Blood in a healthy condition is
naturally sweet to the taste, and red in colour, blood that
deteriorates from natural decay or from disease more or less black.
Blood at its best, before it undergoes deterioration from either
natural decay or from disease, is neither very thick nor very thin. In
the living animal it is always liquid and warm, but, on issuing from
the body, it coagulates in all cases except in the case of the deer,
the roe, and the like animals; for, as a general rule, blood
coagulates unless the fibres be extracted. Bull's blood is the
quickest to coagulate.

Animals that are internally and externally viviparous are more
abundantly supplied with blood than the sanguineous ovipara. Animals
that are in good condition, either from natural causes or from their
health having been attended to, have the blood neither too abundant-as
creatures just after drinking have the liquid inside them in
abundance-nor again very scanty, as is the case with animals when
exceedingly fat. For animals in this condition have pure blood, but
very little of it, and the fatter an animal gets the less becomes
its supply of blood; for whatsoever is fat is destitute of blood.

A fat substance is incorruptible, but blood and all things
containing it corrupt rapidly, and this property characterizes
especially all parts connected with the bones. Blood is finest and
purest in man; and thickest and blackest in the bull and the ass, of
all vivipara. In the lower and the higher parts of the body blood is
thicker and blacker than in the central parts.

Blood beats or palpitates in the veins of all animals alike all
over their bodies, and blood is the only liquid that permeates the
entire frames of living animals, without exception and at all times,
as long as life lasts. Blood is developed first of all in the heart of
animals before the body is differentiated as a whole. If blood be
removed or if it escape in any considerable quantity, animals fall
into a faint or swoon; if it be removed or if it escape in an
exceedingly large quantity they die. If the blood get exceedingly
liquid, animals fall sick; for the blood then turns into something
like ichor, or a liquid so thin that it at times has been known to
exude through the pores like sweat. In some cases blood, when
issuing from the veins, does not coagulate at all, or only here and
there. Whilst animals are sleeping the blood is less abundantly
supplied near the exterior surfaces, so that, if the sleeping creature
be pricked with a pin, the blood does not issue as copiously as it
would if the creature were awake. Blood is developed out of ichor by
coction, and fat in like manner out of blood. If the blood get
diseased, haemorrhoids may ensue in the nostril or at the anus, or the
veins may become varicose. Blood, if it corrupt in the body, has a
tendency to turn into pus, and pus may turn into a solid concretion.

Blood in the female differs from that in the male, for,
supposing the male and female to be on a par as regards age and
general health, the blood in the female is thicker and blacker than in
the male; and with the female there is a comparative superabundance of
it in the interior. Of all female animals the female in man is the
most richly supplied with blood, and of all female animals the
menstruous discharges are the most copious in woman. The blood of
these discharges under disease turns into flux. Apart from the
menstrual discharges, the female in the human species is less
subject to diseases of the blood than the male.

Women are seldom afflicted with varicose veins, with haemorrhoids,
or with bleeding at the nose, and, if any of these maladies supervene,
the menses are imperfectly discharged.

Blood differs in quantity and appearance according to age; in very
young animals it resembles ichor and is abundant, in the old it is
thick and black and scarce, and in middle-aged animals its qualities
are intermediate. In old animals the blood coagulates rapidly, even
blood at the surface of the body; but this is not the case with
young animals. Ichor is, in fact, nothing else but unconcocted
blood: either blood that has not yet been concocted, or that has
become fluid again.

20

We now proceed to discuss the properties of marrow; for this is
one of the liquids found in certain sanguineous animals. All the
natural liquids of the body are contained in vessels: as blood in
veins, marrow in bones other moistures in membranous structures of the
skin

In young animals the marrow is exceedingly sanguineous, but, as
animals grow old, it becomes fatty in animals supplied with fat, and
suet-like in animals with suet. All bones, however, are not supplied
with marrow, but only the hollow ones, and not all of these. For of
the bones in the lion some contain no marrow at all, and some are only
scantily supplied therewith; and that accounts, as was previously
observed, for the statement made by certain writers that the lion is
marrowless. In the bones of pigs it is found in small quantities;
and in the bones of certain animals of this species it is not found at
all.

These liquids, then, are nearly always congenital in animals,
but milk and sperm come at a later time. Of these latter, that
which, whensoever it is present, is secreted in all cases
ready-made, is the milk; sperm, on the other hand, is not secreted out
in all cases, but in some only, as in the case of what are
designated thori in fishes.

Whatever animals have milk, have it in their breasts. All
animals have breasts that are internally and externally viviparous, as
for instance all animals that have hair, as man and the horse; and the
cetaceans, as the dolphin, the porpoise, and the whale-for these
animals have breasts and are supplied with milk. Animals that are
oviparous or only externally viviparous have neither breasts nor milk,
as the fish and the bird.

All milk is composed of a watery serum called 'whey', and a
consistent substance called curd (or cheese); and the thicker the
milk, the more abundant the curd. The milk, then, of non-ambidentals
coagulates, and that is why cheese is made of the milk of such animals
under domestication; but the milk of ambidentals does not coagulate,
nor their fat either, and the milk is thin and sweet. Now the
camel's milk is the thinnest, and that of the human species next after
it, and that of the ass next again, but cow's milk is the thickest.
Milk does not coagulate under the influence of cold, but rather runs
to whey; but under the influence of heat it coagulates and thickens.
As a general rule milk only comes to animals in pregnancy. When the
animal is pregnant milk is found, but for a while it is unfit for use,
and then after an interval of usefulness it becomes unfit for use
again.
In the case of female animals not pregnant a small quantity
of milk has been procured by the employment of special food, and cases
have been actually known where women advanced in years on being
submitted to the process of milking have produced milk, and in some
cases have produced it in sufficient quantities to enable them to
suckle an infant.

The people that live on and about Mount Oeta take such she-goats
as decline the male and rub their udders hard with nettles to cause an
irritation amounting to pain; hereupon they milk the animals,
procuring at first a liquid resembling blood, then a liquid mixed with
purulent matter, and eventually milk, as freely as from females
submitting to the male.

As a general rule, milk is not found in the male of man or of
any other animal, though from time to time it has been found in a
male; for instance, once in Lemnos a he-goat was milked by its dugs
(for it has, by the way, two dugs close to the penis), and was
milked to such effect that cheese was made of the produce, and the
same phenomenon was repeated in a male of its own begetting. Such
occurrences, however, are regarded as supernatural and fraught with
omen as to futurity, and in point of fact when the Lemnian owner of
the animal inquired of the oracle, the god informed him that the
portent foreshadowed the acquisition of a fortune. With some men,
after puberty, milk can be produced by squeezing the breasts; cases
have been known where on their being subjected to a prolonged
milking process a considerable quantity of milk has been educed.

In milk there is a fatty element, which in clotted milk gets to
resemble oil. Goat's milk is mixed with sheep's milk in Sicily, and
wherever sheep's milk is abundant. The best milk for clotting is not
only that where the cheese is most abundant, but that also where the
cheese is driest.

Now some animals produce not only enough milk to rear their young,
but a superfluous amount for general use, for cheese-making and for
storage. This is especially the case with the sheep and the goat,
and next in degree with the cow. Mare's milk, by the way, and milk
of the she-ass are mixed in with Phrygian cheese. And there is more
cheese in cow's milk than in goat's milk; for graziers tell us that
from nine gallons of goat's milk they can get nineteen cheeses at an
obol apiece, and from the same amount of cow's milk, thirty. Other
animals give only enough of milk to rear their young withal, and no
superfluous amount and none fitted for cheese-making, as is the case
with all animals that have more than two breasts or dugs; for with
none of such animals is milk produced in superabundance or used for
the manufacture of cheese.

The juice of the fig and rennet are employed to curdle milk. The
fig-juice is first squeezed out into wool; the wool is then washed and
rinsed, and the rinsing put into a little milk, and if this be mixed
with other milk it curdles Rennet is a kind of milk, for it is found
in the stomach of the animal while it is yet suckling.

21

Rennet then consists of milk with an admixture of fire, which
comes from the natural heat of the animal, as the milk is concocted.
All ruminating animals produce rennet, and, of ambidentals, the
hare. Rennet improves in quality the longer it is kept; and cow's
rennet, after being kept a good while, and also hare's rennet, is good
for diarrhoea, and the best of all rennet is that of the young deer.

In milk-producing animals the comparative amount of the yield
varies with the size of the animal and the diversities of pasturage.
For instance, there are in Phasis small cattle that in all cases
give a copious supply of milk, and the large cows in Epirus yield each
one daily some nine gallons of milk, and half of this from each pair
of teats, and the milker has to stand erect, stooping forward a
little, as otherwise, if he were seated, he would be unable to reach
up to the teats. But, with the exception of the ass, all the
quadrupeds in Epirus are of large size, and relatively, the cattle and
the dogs are the largest. Now large animals require abundant
pasture, and this country supplies just such pasturage, and also
supplies diverse pasture grounds to suit the diverse seasons of the
year. The cattle are particularly large, and likewise the sheep of the
so-called Pyrrhic breed, the name being given in honour of King
Pyrrhus.

Some pasture quenches milk, as Median grass or lucerne, and that
especially in ruminants; other feeding renders it copious, as
cytisus and vetch; only, by the way, cytisus in flower is not
recommended, as it has burning properties, and vetch is not good for
pregnant kine, as it causes increased difficulty in parturition.
However, beasts that have access to good feeding, as they are
benefited thereby in regard to pregnancy, so also being well nourished
produce milk in plenty. Some of the leguminous plants bring milk in
abundance, as for instance, a large feed of beans with the ewe, the
common she-goat, the cow, and the small she-goat; for this feeding
makes them drop their udders. And, by the way, the pointing of the
udder to the ground before parturition is a sign of there being plenty
of milk coming.

Milk remains for a long time in the female, if she be kept from
the male and be properly fed, and, of quadrupeds, this is especially
true of the ewe; for the ewe can be milked for eight months. As a
general rule, ruminating animals give milk in abundance, and milk
fitted for cheese manufacture. In the neighbourhood of Torone cows run
dry for a few days before calving, and have milk all the rest of the
time. In women, milk of a livid colour is better than white for
nursing purposes; and swarthy women give healthier milk than fair
ones. Milk that is richest in cheese is the most nutritious, but
milk with a scanty supply of cheese is the more wholesome for
children.

22

All sanguineous animals eject sperm. As to what, and how, it
contributes to generation, these questions will be discussed in
another treatise. Taking the size of his body into account, man
emits more sperm than any other animal. In hairy-coated animals the
sperm is sticky, but in other animals it is not so. It is white in all
cases, and Herodotus is under a misapprehension when he states that
the Aethiopians eject black sperm.

Sperm issues from the body white and consistent, if it be healthy,
and after quitting the body becomes thin and black. In frosty
weather it does not coagulate, but gets exceedingly thin and watery
both in colour and consistency; but it coagulates and thickens under
the influence of heat. If it be long in the womb before issuing out,
it comes more than usually thick; and sometimes it comes out dry and
compact. Sperm capable of impregnating or of fructification sinks in
water; sperm incapable Of producing that result dissolves away. But
there is no truth in what Ctesias has written about the sperm of the
elephant.

Book IV

1

We have now treated, in regard to blooded animals of the parts
they have in common and of the parts peculiar to this genus or that,
and of the parts both composite and simple, whether without or within.
We now proceed to treat of animals devoid of blood. These animals
are divided into several genera.

One genus consists of so-called 'molluscs'; and by the term
'mollusc' we mean an animal that, being devoid of blood, has its
flesh-like substance outside, and any hard structure it may happen
to have, inside-in this respect resembling the red-blooded animals,
such as the genus of the cuttle-fish.

Another genus is that of the malacostraca. These are animals
that have their hard structure outside, and their soft or fleshlike
substance inside, and the hard substance belonging to them has to be
crushed rather than shattered; and to this genus belongs the
crawfish and the crab.

A third genus is that of the ostracoderms or 'testaceans'. These
are animals that have their hard substance outside and their
flesh-like substance within, and their hard substance can be shattered
but not crushed; and to this genus belong the snail and the oyster.

The fourth genus is that of insects; and this genus comprehends
numerous and dissimilar species. Insects are creatures that, as the
name implies, have nicks either on the belly or on the back, or on
both belly and back, and have no one part distinctly osseous and no
one part distinctly fleshy, but are throughout a something
intermediate between bone and flesh; that is to say, their body is
hard all through, inside and outside. Some insects are wingless,
such as the iulus and the centipede; some are winged, as the bee,
the cockchafer, and the wasp; and the same kind is in some cases
both winged and wingless, as the ant and the glow-worm.

In molluscs the external parts are as follows: in the first place,
the so-called feet; secondly, and attached to these, the head;
thirdly, the mantle-sac, containing the internal parts, and
incorrectly designated by some writers the head; and, fourthly, fins
round about the sac. (See diagram. ) In all molluscs the head is found
to be between the feet and the belly. All molluscs are furnished with
eight feet, and in all cases these feet are severally furnished with
a double row of suckers, with the exception of one single species of
poulpe or octopus. The sepia, the small calamary and the large
calamary have an exceptional organ in a pair of long arms or
tentacles, having at their extremities a portion rendered rough by
the presence of two rows of suckers; and with these arms or tentacles
they apprehend their food and draw it into their mouths, and in
stormy weather they cling by them to a rock and sway about in the
rough water like ships lying at anchor. They swim by the aid of the
fins that they have about the sac. In all cases their feet are
furnished with suckers.

The octopus, by the way, uses his feelers either as feet or hands;
with the two which stand over his mouth he draws in food, and the last
of his feelers he employs in the act of copulation; and this last one,
by the way, is extremely sharp, is exceptional as being of a whitish
colour, and at its extremity is bifurcate; that is to say, it has an
additional something on the rachis, and by rachis is meant the
smooth surface or edge of the arm on the far side from the suckers.
(See diagram. )

In front of the sac and over the feelers they have a hollow
tube, by means of which they discharge any sea-water that they may
have taken into the sac of the body in the act of receiving food by
the mouth. They can shift the tube from side to side, and by means
of it they discharge the black liquid peculiar to the animal.

Stretching out its feet, it swims obliquely in the direction of
the so-called head, and by this mode of swimming it can see in
front, for its eyes are at the top, and in this attitude it has its
mouth at the rear. The 'head', while the creature is alive, is hard,
and looks as though it were inflated. It apprehends and retains
objects by means of the under-surface of its arms, and the membrane in
between its feet is kept at full tension; if the animal get on to
the sand it can no longer retain its hold.

There is a difference between the octopus and the other molluscs
above mentioned: the body of the octopus is small, and his feet are
long, whereas in the others the body is large and the feet short; so
short, in fact, that they cannot walk on them. Compared with one
another, the teuthis, or calamary, is long-shaped, and the sepia
flat-shaped; and of the calamaries the so-called teuthus is much
bigger than the teuthis; for teuthi have been found as much as five
ells long. Some sepiae attain a length of two ells, and the feelers of
the octopus are sometimes as long, or even longer. The species teuthus
is not a numerous one; the teuthus differs from the teuthis in
shape; that is, the sharp extremity of the teuthus is broader than
that of the other, and, further, the encircling fin goes all round the
trunk, whereas it is in part lacking in the teuthis; both animals
are pelagic.

In all cases the head comes after the feet, in the middle of the
feet that are called arms or feelers. There is here situated a
mouth, and two teeth in the mouth; and above these two large eyes, and
betwixt the eyes a small cartilage enclosing a small brain; and within
the mouth it has a minute organ of a fleshy nature, and this it uses
as a tongue, for no other tongue does it possess. Next after this,
on the outside, is what looks like a sac; the flesh of which it is
made is divisible, not in long straight strips, but in annular flakes;
and all molluscs have a cuticle around this flesh. Next after or at
the back of the mouth comes a long and narrow oesophagus, and close
after that a crop or craw, large and spherical, like that of a bird;
then comes the stomach, like the fourth stomach in ruminants; and
the shape of it resembles the spiral convolution in the trumpet-shell;
from the stomach there goes back again, in the direction of the mouth,
thin gut, and the gut is thicker than the oesophagus. (See diagram. )

Molluscs have no viscera, but they have what is called a
mytis, and on it a vessel containing a thick black juice; in the sepia
or cuttle-fish this vessel is the largest, and this juice is most
abundant. All molluscs, when frightened, discharge such a juice, but
the discharge is most copious in the cuttle-fish. The mytis, then,
is situated under the mouth, and the oesophagus runs through it; and
down below at the point to which the gut extends is the vesicle of the
black juice, and the animal has the vesicle and the gut enveloped in
one and the same membrane, and by the same membrane, same orifice
discharges both the black juice and the residuum. The animals have
also certain hair-like or furry growths in their bodies.

In the sepia, the teuthis, and the teuthus the hard parts are
within, towards the back of the body; those parts are called in one
the sepium, and in the other the 'sword'. They differ from one
another, for the sepium in the cuttle-fish and teuthus is hard and
flat, being a substance intermediate between bone and fishbone, with
(in part) a crumbling, spongy texture, but in the teuthis the part
is thin and somewhat gristly. These parts differ from one another in
shape, as do also the bodies of the animals. The octopus has nothing
hard of this kind in its interior, but it has a gristly substance
round the head, which, if the animal grows old, becomes hard.

The females differ from the males. The males have a duct in
under the oesophagus, extending from the mantle-cavity to the lower
portion of the sac, and there is an organ to which it attaches,
resembling a breast; (see diagram) in the female there are two of
these organs, situated higher up; (see diagram) with both sexes there
are underneath these organs certain red formations. The egg of the
octopus is single, uneven on its surface, and of large size; the
fluid substance within is all uniform in colour, smooth, and in
colour white; the size of the egg is so great as to fill a vessel
larger than the creature's head. The sepia has two sacs, and inside
them a number of eggs, like in appearance to white hailstones. For
the disposition of these parts I must refer to my anatomical
diagrams.

The males of all these animals differ from the females, and the
difference between the sexes is most marked in the sepia; for the back
of the trunk, which is blacker than the belly, is rougher in the
male than in the female, and in the male the back is striped, and
the rump is more sharply pointed.

There are several species of the octopus. One keeps close to the
surface, and is the largest of them all, and near the shore the size
is larger than in deep water; and there are others, small,
variegated in colour, which are not articles of food. There are two
others, one called the heledone, which differs from its congeners in
the length of its legs and in having one row of suckers-all the rest
of the molluscs having two,-the other nicknamed variously the
bolitaina or the 'onion,' and the ozolis or the 'stinkard'.

There are two others found in shells resembling those of the
testaceans. One of them is nicknamed by some persons the nautilus or
the pontilus, or by others the 'polypus' egg'; and the shell of this
creature is something like a separate valve of a deep scallop-shell.
This polypus lives very often near to the shore, and is apt to be
thrown up high and dry on the beach; under these circumstances it is
found with its shell detached, and dies by and by on dry land. These
polypods are small, and are shaped, as regards the form of their
bodies, like the bolbidia. There is another polypus that is placed
within a shell like a snail; it never comes out of the shell, but
lives inside the shell like the snail, and from time to time protrudes
its feelers.

So much for molluscs.

2

With regard to the Malacostraca or crustaceans, one species is
that of the crawfish, and a second, resembling the first, is that of
the lobster; the lobster differing from the crawfish in having
claws, and in a few other respects as well. Another species is that of
the carid, and another is that of the crab, and there are many kinds
both of carid and of crab.

Of carids there are the so-called cyphae, or 'hunch-backs', the
crangons, or squillae, and the little kind, or shrimps, and the little
kind do not develop into a larger kind.

Of the crab, the varieties are indefinite and incalculable. The
largest of all crabs is one nicknamed Maia, a second variety is the
pagarus and the crab of Heracleotis, and a third variety is the
fresh-water crab; the other varieties are smaller in size and
destitute of special designations. In the neighbourhood of Phoenice
there are found on the beach certain crabs that are nicknamed the
'horsemen', from their running with such speed that it is difficult to
overtake them; these crabs, when opened, are usually found empty,
and this emptiness may be put down to insufficiency of nutriment.
(There is another variety, small like the crab, but resembling in
shape the lobster. ) All these animals, as has been stated, have
their hard and shelly part outside, where the skin is in other
animals, and the fleshy part inside; and the belly is more or less
provided with lamellae, or little flaps, and the female here
deposits her spawn.

The crawfishes have five feet on either side, including the
claws at the end; and in like manner the crabs have ten feet in all,
including the claws. Of the carids, the hunch-backed, or prawns,
have five feet on either side, which are sharp-pointed-those towards
the head; and five others on either side in the region of the belly,
with their extremities flat; they are devoid of flaps on the under
side such as the crawfish has, but on the back they resemble the
crawfish. (See diagram. )It is very different with the crangon, or
squilla; it has four front legs on either side, then three thin ones
close behind on either side, and the rest of the body is for the most
part devoid of feet. (See diagram. ) Of all these animals the feet
bend out obliquely, as is the case with insects; and the claws, where
claws are found, turn inwards. The crawfish has a tail, and five fins
on it; and the round-backed carid has a tail and four fins; the
squilla also has fins at the tail on either side. In the case of both
the hump-backed carid and the squilla the middle art of the tail is
spinous: only that in the squilla the part is flattened and in the
carid it is sharp-pointed. Of all animals of this genus the crab is
the only one devoid of a rump; and, while the body of the carid and
the crawfish is elongated, that of the crab is rotund.

In the crawfish the male differs from the female: in the female
the first foot is bifurcate, in the male it is undivided; the
belly-fins in the female are large and overlapping on the neck,
while in the male they are smaller and do not overlap; and, further,
on the last feet of the male there are spur-like projections, large
and sharp, which projections in the female are small and smooth.
Both male and female have two antennae in front of the eyes, large and
rough, and other antennae underneath, small and smooth. The eyes of
all these creatures are hard and beady, and can move either to the
inner or to the outer side. The eyes of most crabs have a similar
facility of movement, or rather, in the crab this facility is
developed in a higher degree. (See diagram. )

The lobster is all over grey-coloured, with a mottling of black.
Its under or hinder feet, up to the big feet or claws, are eight in
number; then come the big feet, far larger and flatter at the tips
than the same organs in the crawfish; and these big feet or claws
are exceptional in their structure, for the right claw has the extreme
flat surface long and thin, while the left claw has the
corresponding surface thick and round. Each of the two claws,
divided at the end like a pair of jaws, has both below and above a set
of teeth: only that in the right claw they are all small and
saw-shaped, while in the left claw those at the apex are saw-shaped
and those within are molar-shaped, these latter being, in the under
part of the cleft claw, four teeth close together, and in the upper
part three teeth, not close together. Both right and left claws have
the upper part mobile, and bring it to bear against the lower one, and
both are curved like bandy-legs, being thereby adapted for
apprehension and constriction. Above the two large claws come two
others, covered with hair, a little underneath the mouth; and
underneath these the gill-like formations in the region of the
mouth, hairy and numerous. These organs the animal keeps in
perpetual motion; and the two hairy feet it bends and draws in towards
its mouth. The feet near the mouth are furnished also with delicate
outgrowing appendages. Like the crawfish, the lobster has two teeth,
or mandibles, and above these teeth are its antennae, long, but
shorter and finer by far than those of the crawfish, and then four
other antennae similar in shape, but shorter and finer than the
others. Over these antennae come the eyes, small and short, not
large like the eyes of the crawfish. Over the eyes is a peaky rough
projection like a forehead, larger than the same part in the crawfish;
in fact, the frontal part is more pointed and the thorax is much
broader in the lobster than in the crawfish, and the body in general
is smoother and more full of flesh. Of the eight feet, four are
bifurcate at the extremities, and four are undivided. The region of
the so-called neck is outwardly divided into five divisions, and
sixthly comes the flattened portion at the end, and this portion has
five flaps, or tail-fins; and the inner or under parts, into which the
female drops her spawn, are four in number and hairy, and on each of
the aforesaid parts is a spine turned outwards, short and straight.
The body in general and the region of the thorax in particular are
smooth, not rough as in the crawfish; but on the large claws the outer
portion has larger spines. There is no apparent difference between the
male and female, for they both have one claw, whichever it may be,
larger than the other, and neither male nor female is ever found
with both claws of the same size.

All crustaceans take in water close by the mouth. The crab
discharges it, closing up, as it does so, a small portion of the same,
and the crawfish discharges it by way of the gills; and, by the way,
the gill-shaped organs in the crawfish are very numerous.

The following properties are common to all crustaceans: they
have in all cases two teeth, or mandibles (for the front teeth in
the crawfish are two in number), and in all cases there is in the
mouth a small fleshy structure serving for a tongue; and the stomach
is close to the mouth, only that the crawfish has a little
oesophagus in front of the stomach, and there is a straight gut
attached to it. This gut, in the crawfish and its congeners, and in
the carids, extends in a straight line to the tail, and terminates
where the animal discharges the residuum, and where the female
deposits her spawn; in the crab it terminates where the flap is
situated, and in the centre of the flap. (And by the way, in all these
animals the spawn is deposited outside. ) Further, the female has the
place for the spawn running along the gut. And, again, all these
animals have, more or less, an organ termed the 'mytis', or
'poppyjuice'.

We must now proceed to review their several differentiae.

The crawfish then, as has been said, has two teeth, large and
hollow, in which is contained a juice resembling the mytis, and in
between the teeth is a fleshy substance, shaped like a tongue. After
the mouth comes a short oesophagus, and then a membranous stomach
attached to the oesophagus, and at the orifice Of the stomach are
three teeth, two facing one another and a third standing by itself
underneath. Coming off at a bend from the stomach is a gut, simple and
of equal thickness throughout the entire length of the body until it
reaches the anal vent.

These are all common properties of the crawfish, the carid, and
the crab; for the crab, be it remembered, has two teeth.

Again, the crawfish has a duct attached all the way from the chest
to the anal vent; and this duct is connected with the ovary in the
female, and with the seminal ducts in the male. This passage is
attached to the concave surface of the flesh in such a way that the
flesh is in betwixt the duct and the gut; for the gut is related to
the convexity and this duct to the concavity, pretty much as is
observed in quadrupeds. And the duct is identical in both the sexes;
that is to say, the duct in both is thin and white, and charged with a
sallow-coloured moisture, and is attached to the chest.

(The following are the properties of the egg and of the convolutes
in the carid. )

The male, by the way, differs from the female in regard to its
flesh, in having in connexion with the chest two separate and distinct
white substances, resembling in colour and conformation the
tentacles of the cuttle-fish, and they are convoluted like the 'poppy'
or quasi-liver of the trumpet-shell. These organs have their
starting-point in 'cotyledons' or papillae, which are situated under
the hindmost feet; and hereabouts the flesh is red and blood-coloured,
but is slippery to the touch and in so far unlike flesh. Off from
the convolute organ at the chest branches off another coil about as
thick as ordinary twine; and underneath there are two granular seminal
bodies in juxta-position with the gut. These are the organs of the
male. The female has red-coloured eggs, which are adjacent to the
stomach and to each side of the gut all along to the fleshy parts,
being enveloped in a thin membrane.

Such are the parts, internal and external, of the carid.

3

The inner organs of sanguineous animals happen to have specific
designations; for these animals have in all cases the inner viscera,
but this is not the case with the bloodless animals, but what they
have in common with red-blooded animals is the stomach, the
oesophagus, and the gut.

With regard to the crab, it has already been stated that it has
claws and feet, and their position has been set forth; furthermore,
for the most part they have the right claw bigger and stronger than
the left. It has also been stated' that in general the eyes of the
crab look sideways. Further, the trunk of the crab's body is single
and undivided, including its head and any other part it may possess.
Some crabs have eyes placed sideways on the upper part, immediately
under the back, and standing a long way apart, and some have their
eyes in the centre and close together, like the crabs of Heracleotis
and the so-called 'grannies'. The mouth lies underneath the eyes,
and inside it there are two teeth, as is the case with the crawfish,
only that in the crab the teeth are not rounded but long; and over the
teeth are two lids, and in betwixt them are structures such as the
crawfish has besides its teeth. The crab takes in water near by the
mouth, using the lids as a check to the inflow, and discharges the
water by two passages above the mouth, closing by means of the lids
the way by which it entered; and the two passage-ways are underneath
the eyes. When it has taken in water it closes its mouth by means of
both lids, and ejects the water in the way above described. Next after
the teeth comes the oesophagus, very short, so short in fact that
the stomach seems to come straightway after the mouth. Next after
the oesophagus comes the stomach, two-horned, to the centre of which
is attached a simple and delicate gut; and the gut terminates
outwards, at the operculum, as has been previously stated. (The crab
has the parts in between the lids in the neighbourhood of the teeth
similar to the same parts in the crawfish. ) Inside the trunk is a
sallow juice and some few little bodies, long and white, and others
spotted red. The male differs from the female in size and breadth, and
in respect of the ventral flap; for this is larger in the female
than in the male, and stands out further from the trunk, and is more
hairy (as is the case also with the female in the crawfish).

So much, then, for the organs of the malacostraca or crustacea.

4

With the ostracoderma, or testaceans, such as the land-snails
and the sea-snails, and all the 'oysters' so-called, and also with the
sea-urchin genus, the fleshy part, in such as have flesh, is similarly
situated to the fleshy part in the crustaceans; in other words, it
is inside the animal, and the shell is outside, and there is no hard
substance in the interior. As compared with one another the testaceans
present many diversities both in regard to their shells and to the
flesh within. Some of them have no flesh at all, as the sea-urchin;
others have flesh, but it is inside and wholly hidden, except the
head, as in the land-snails, and the so-called cocalia, and, among
pelagic animals, in the purple murex, the ceryx or trumpet-shell,
the sea-snail, and the spiral-shaped testaceans in general. Of the
rest, some are bivalved and some univalved; and by 'bivalves' I mean
such as are enclosed within two shells, and by 'univalved' such as are
enclosed within a single shell, and in these last the fleshy part is
exposed, as in the case of the limpet. Of the bivalves, some can
open out, like the scallop and the mussel; for all such shells are
grown together on one side and are separate on the other, so as to
open and shut. Other bivalves are closed on both sides alike, like the
solen or razor-fish. Some testaceans there are, that are entirely
enveloped in shell and expose no portion of their flesh outside, as
the tethya or ascidians.

Again, in regard to the shells themselves, the testaceans
present differences when compared with one another. Some are
smooth-shelled, like the solen, the mussel, and some clams, viz. those
that are nicknamed 'milkshells', while others are rough-shelled,
such as the pool-oyster or edible oyster, the pinna, and certain
species of cockles, and the trumpet shells; and of these some are
ribbed, such as the scallop and a certain kind of clam or cockle,
and some are devoid of ribs, as the pinna and another species of clam.
Testaceans also differ from one another in regard to the thickness
or thinness of their shell, both as regards the shell in its
entirety and as regards specific parts of the shell, for instance, the
lips; for some have thin-lipped shells, like the mussel, and others
have thick-lipped shells, like the oyster. A property common to the
above mentioned, and, in fact, to all testaceans, is the smoothness of
their shells inside. Some also are capable of motion, like the
scallop, and indeed some aver that scallops can actually fly, owing to
the circumstance that they often jump right out of the apparatus by
means of which they are caught; others are incapable of motion and are
attached fast to some external object, as is the case with the
pinna. All the spiral-shaped testaceans can move and creep, and even
the limpet relaxes its hold to go in quest of food. In the case of the
univalves and the bivalves, the fleshy substance adheres to the
shell so tenaciously that it can only be removed by an effort; in
the case of the stromboids, it is more loosely attached. And a
peculiarity of all the stromboids is the spiral twist of the shell
in the part farthest away from the head; they are also furnished
from birth with an operculum. And, further, all stromboid testaceans
have their shells on the right hand side, and move not in the
direction of the spire, but the opposite way. Such are the diversities
observed in the external parts of these animals.

The internal structure is almost the same in all these
creatures, and in the stromboids especially; for it is in size that
these latter differ from one another, and in accidents of the nature
of excess or defect. And there is not much difference between most
of the univalves and bivalves; but, while those that open and shut
differ from one another but slightly, they differ considerably from
such as are incapable of motion. And this will be illustrated more
satisfactorily hereafter.

The spiral-shaped testaceans are all similarly constructed, but
differ from one another, as has been said, in the way of excess or
defect (for the larger species have larger and more conspicuous
organs, and the smaller have smaller and less conspicuous), and,
furthermore, in relative hardness or softness, and in other such
accidents or properties. All the stromboids, for instance, have the
flesh that extrudes from the mouth of the shell, hard and stiff;
some more, and some less. From the middle of this protrudes the head
and two horns, and these horns are large in the large species, but
exceedingly minute in the smaller ones. The head protrudes from them
all in the same way; and, if the animal be alarmed, the head draws
in again. Some of these creatures have a mouth and teeth, as the
snail; teeth sharp, and small, and delicate. They have also a
proboscis just like that of the fly; and the proboscis is
tongue-shaped. The ceryx and the purple murex have this organ firm and
solid; and just as the myops, or horse-fly, and the oestrus, or
gadfly, can pierce the skin of a quadruped, so is that proboscis
proportionately stronger in these testaceans; for they bore right
through the shells of other shell-fish on which they prey. The stomach
follows close upon the mouth, and, by the way, this organ in the snail
resembles a bird's crop. Underneath come two white firm formations,
mastoid or papillary in form; and similar formations are found in
the cuttle-fish also, only that they are of a firmer consistency in
the cuttle-fish.