THE SKELETON. 
The number of bones in the skeleton of the cat varies 
with its age, since two or more bones separate in the young 
may form one mass in the old animal. The three portions 
of the innominate bone which are distinct (Fig. 38) in the 
young, become fused in the adult. In very old age many 
sutures of the skull become partially or wholly obliterated. 
In the young adult cat the number of bones, exclusive of the 
teeth, ear bones, chevron bones, and sesamoid bones, is 
about 233. The sacrum is reckoned as one bone, though 
composed of three coalesced vertebre. The structure and 
embryology of the teeth show that they belong to a different 
category from the bones. The ossicula auditus, or ear 
bones, are the malleus, incus, and stapes of the middle ear. 
The chevron bones are eight in number, attached to the 
ventral side of the vertebrze of the tail. The sesamoid bones 
number about forty, of which the patella, or knee-cap, is the 
largest. They are formed in the tendons where there is 
much pressure or friction, as upon the volar surface of the 
metacarpus. The outline on page 22 gives the classifica- 
tion, names, and number of the different bones of the 
skeleton. 
GENERAL TERMS USED IN DESCRIPTION OF 
BONES. 
In reference to shape the bones are spoken of as long, 
short, flat, and irregular. Long bones are those having a 
shaft or diaphysis in which is a cavity filled with marrow, 
and two enlarged extremities or epiphyses (Fig. 13): 
femur, fibula, metacarpals, and phalanges. Short bones 
21 
