842 
ZOOLOGY. 
Crustacea have it; also insects, both in their perfect and 
larva states. It is shed in the latter several times before the 
change to the state of chrysalis; seven times in most of the 
butterflies and bombvces. 
It is very distinct in the vermes, as in the common earth¬ 
worm and leech, which often shed it. In the sipunculus sac- 
catus it is loose and not adherent to the surface. 
All fishes, without exception, are covered with scales, which 
are bare in those which inhabit the open sea, but on the 
contrary are covered with a mucous membrane in those 
which live on coasts, or in fresh water. It is remarkable 
that the colour of the skin in some fishes, as for instance, the 
mullet, (mullus barbatus) depends on that of the liver. The 
scales are not changed like hair and feathers, but are peren¬ 
nial ; and are said to receive yearly an additional layer to 
their laminated texture, from the number of which the age 
of the animal may consequently be determined. 
The very various integuments which are found in amphi¬ 
bia, consisting of shields, rings, scales, or simple skin, are 
covered externally with cuticle, which is frequently separated 
in many of these animals, as in the snake, (forming what is 
called snakes-shirt leberis-, senecta,) and water-newt. 
The process of separation is repeated every week for some 
time in the latter animal, particularly in spring and autumn. 
Some, which have small fine scales, as the chameleon, or a 
simple skin, as some frogs, change their colour occasionally, 
either from difference in the light or warmth, or from the 
effect of their passions. 
The integuments of birds consist of three parts. Some are 
furnished with hair in particular situations ; as thevultur bar¬ 
batus, the raven, and the turkey. Others, as the cassowary, 
have long spines like fish-bones in their wings, which approach 
in the tubular structure of their roots, to the formation of feath¬ 
ers; the universal and peculiar covering of thisclassof animals. 
The particular differences in the formation of the feathers are 
innumerable. Among the most remarkable are the small 
scale-like feathers (squamulse ciliatae) of the penguin’s wing; 
and the horny, flat, and pointed processes on the tip of the 
neck, and wing-feathers of the common fowl in its wild 
state; and on those of the Bohemian chatterer (ampelis gar- 
rulus). Several birds in difftrent orders have two or more 
feathers arising from a common quill. 
Blumenbach found in a young ostrich, which had just 
quitted the egg, as many as twenty feathers on the back, 
proceeding from a single barrel. 
The cetacea have the epidermis quite smooth; and marked 
with none of those lines which are so often seen in the other 
mammalia. 
It is detached from the surface, in the form of small scales, 
in all the mammalia, except the whales; and in some this 
happens chiefly at the season when their hair is shed. It 
gives the skin a branny appearance. 
It is in the rete mucosum that the colour of the skin re¬ 
sides ; but this part possesses, in very few instances, any 
brilliancy of colour in the mammalia. It is of a beautiful 
red and violet on the nose and buttocks of some baboons; 
and silvery white on the abdomen of the cetacea. It is re¬ 
markably thick on these animals; being about the sixteenth 
of an inch on the back, and such parts as are of a black co¬ 
lour. 
The vascular net-work, says De Biainville, in the work 
referred to by Blumenbach, which is situated immediately 
over the cutis, occupying its whole surface, is in general of 
an exceedingly thin texture; it is formed entirely of arterial, 
venous, and lymphatic vessels, which undergo many complex 
ramifications and anastomoses; this net-work is spread over 
the projections situated on the surface of the cutis. The 
pigmentum does not perhaps exist in all animals; it forms at 
the surface of the vascular net-work a layer more or less de¬ 
fined, of slight consistence, semi-fluid, and in effect composed 
entirely of very minute grains, agglutinated to each other, 
without any organic continuity between their own particles 
or with the other portions of the skin ; it is a sort of artificial 
membrane or depository, which is variously coloured, and 
which seems to be exhaled by the parietes of the veins. This 
pigmentum and the vascular net-work are both crossed by 
the nervous extremities which meet at the surface of the skin, 
sometimes under the form of papillae. These two parts of the 
skin are those, which, since the time of Malpighi, have been 
known by the name of Malpighi’s net-work, corpus reticulare, 
reticulum mucosum, on account of the sortofnet-work which 
they form for the passage, not only of the nervous papillae, 
but also of the accessory parts. They are both in my 
opinion, says De Biainville, the source of the colouring mat¬ 
ter, and the pigmentum is the depository of that matter. 
The cutis of mammalia varies infinitely in thickness. It 
is extremely thin and delicate in the wing of the bat, and on 
the contrary exceedingly thick in the rhinoceros, elephant, 
&c. also in the web-footed animals, particularly the walrus. 
The form of the papillee on its external surface is very various 
in the different animals of this class, as, indeed, in different 
parts of the same animal. They are sometimes threadlike, as 
on the paws of the bear, and are very elegant on the teats of 
the true whale (balsena mysticetus). 
The colour of the rete mucosum varies, even in individuals 
of the same species, as in the different races of mankind. It 
is thickest in some cetacea. 
In some spotted domestic animals, particularly the sheep, 
rabbit, and dog, there is a remarkable connexion between 
the colour of the palate, and even sometimes of the iris, and 
that of the skin; for spots of similar descriptions are found 
in both parts. 
The cuticle is often of very unequal thickness in particular 
parts, from the different purposes to which it is destined. 
Thus it is very thin on the points of the fingers in apes and 
baboons, when compared with its great thickness where it 
covers the callosities on which they sit. In various multungula, 
particularly the elephant, it forms a kind of horny processes. 
Hairs, at least single ones, are found in all adult mam¬ 
malia, even without excepting the cetacea. In various states 
of thickness and strength they constitute every intermediate 
substance, from the finest wool to the strongest quills of the 
porcupine. 
We may here take notice of some organs destined for the 
secretion of peculiar fluids. 
1st. Both species of the elephant, viz. the African and 
Indian, have a considerable gland at the temple, between the 
eye and meatus auditorius, secreting in the rutting season a 
brownish juice, which is discharged through an opening in 
the skin. 
2d. A remarkable gland is found on the back of the musk- 
hog, or pecari (sus taja^u), over the sacrum, It is of a con¬ 
siderable size (between two and three inches long, and above 
an inch broad) and is composed of several lobules, whose 
ducts join into one canal, which penetrates the skin. It fur¬ 
nishes a secretion of a very pleasant musk-like odour, from 
which Tyson denominated the animal aper moschiferus. 
The opening of this part on the back has been described by 
many authors as the navel. 
3d. In most of the ruminating animals, and in the hare, 
there are cavities in the groins, near the genitals, called by 
Pallas antra inguinalia, and containing a strong scented se¬ 
baceous substance, secreted from glands which lie under the 
integuments. 
4th. Some other mammalia have pouches on the abdo¬ 
men, covered internally with a fine hair, and containing fatty 
secretions of peculiar odours. Of this kind are the bags near 
the anus of the badger, and that which contains the teats of 
the female marsupial animals. 
5th. There are also in the badger and the opossum, as 
well as in several other carnivorous animals, (both among the 
digitala and palmata,) peculiar glands and bags at the end of 
the rectum, secreting a yellow substance of a strong and dis¬ 
agreeable smell in its recent state, and which frequently gives 
to their excrement a kind of musk-like odour. These glands 
may be seen very well in the cat. Their secretion possesses 
that strong disagreeable odour which characterizes so remark¬ 
ably many animals of this order, as the fox and all the weasel 
tribe. 
