COMPARATIVE ANATOM V. 
III. Infamia, tlie animalcules of infu- 
sions. 
1. Vorticella, wheel-animal. 
а. Brachionus. 
3. Vibrio, eel of vinegai'. 
4. Volvox. 
б. Monas. 
IV. Inhabitants of corals, corallines, 
sponges, &c. 
COMPARATIVE OSTEOLOGY. 
It has been asserted, that the bones in 
some instances have not their ordinary white 
colour. Thus the amedabad finch, (frin- 
gilla amandava,) and the golden pheasant, 
have been said to possess yellow bones ; 
but this is not true. In tlie garpike (esox 
belone) the bones are green ; and in some 
varieties of the common fowl in the East 
Indies they are black; but this colour is 
said by Mr. Hunter to reside in the pe- 
riosteum. 
The opinion of Aristotle, that the bones 
of the lion had no marrow, is totally un- 
founded. 
The bones of the cranium are much more 
completely ossified at the time of birth, 
in the mammalia, thau in man. In tlie 
former the fontanells are hardly discerni- 
ble. When we compare the pelvis, and 
the whole mechanism of parturition in the 
w’oman, with those of the female quadru- 
ped, the cause of this difference appears, 
we then discover, why the yielding and 
over lapping of the large bones of the cra- 
nium, wliich is chiefly eflected by the fon- 
tanells, is only required to facilitate tlie 
birth of the human fetus. 
Tlie skeleton remains constantly carti- 
laginous in some animals ; such as the 
skate, shark, sturgeon, and all those fishes, 
which, from this circumstance, have been 
denominated cartilaginous. The bones of 
birds are almost universally hollow ; but 
their cavities, which never confciin marrow, 
are filled wilh air. This organization unites 
the advantages of strength and liglitnes-S. 
Crustaceous animals, (crab, lobster, &c.) 
have a skeleton which surrounds and con- 
tains their soft parts, and which serves at 
the same time the purposes of a skin. 
When it has attained ilsperfectconsistence, 
it grows no more : but as the soft parts 
still increase, the shell separates, and is de- 
tached, being succeeded by a larger one. 
This new covering is partly formed before 
the other separates : it is at first soft, sen- 
sible, and vascular; but it speedily acquires 
a hard consistence by the increased dcpo< 
sition of calcareous matter. 
Some of the mollusca have hard parts in 
the interior of their body. The common 
cuttlefish (sepia officinalis) has a white, 
firm, and calcareous mass of an oval form, 
and slightly convex on its two surfaces, 
commonly known by the name of the cut- 
tlefish-bone, contained in the substance of 
its body. It has no connection with any 
soft part, whence it appears completely as 
a foreign body : no vessel nor nerve can 
be perceived to enter it ; nor does it re- 
ceive the attachment of any tendon. In 
the cahnar (sepia loligo), this body resem- 
bles horn in its appearance ; it is transpa- 
rent, hard, and brittle. Its form resem- 
bles that of a leaf! except that it is larger ; 
and sometimes that of a sword-blade. These 
parts must grow like shells, by the simple 
addition of successive layers. 
In the vertebral animals, the bony parts 
of the body are composed of a gelatinous 
substance, united to phosphate of lime. 
But in the low^er or.lere of animals, the 
hard parts are composed chiefly or entirely 
of carbonate of lime. This is the case 
with the shells of all the testacea. 
SKELETON OF MAMMALIA, 
The form of the different mammalia, par- 
ticularly the fourfooted ones, varies consi- 
derably ; and their skeletons must be mark- 
ed by corresponding differences. Yet these 
varieties may be included, at least for the 
greatest part, under the following peculia- 
rities ; which serve to distinguish their ske- 
letons from those of birds. 
The skeletons of 
mammalia possess : 
1. A skull with 
genuine sutures, at 
least with very few 
exceptions; as per- 
haps the elephant, 
and the duck-billed 
animal (ornithorhyn- 
cus). 
2. Jaws furnished 
with teeth. 
Except the ant- 
eaters, the maais, 
the balama (whale). 
3. An upper jaw, 
which does not 
move. 
Those of birds are 
distinguished by : 
1. A skull whioh 
has not real sutures, 
at least in the adult. 
2. A bill without 
teeth. 
3. An upper jaw, 
which does move. 
There are some 
exceptions, viz. the 
rliinoceros bud. 
