OSTEOLOGICAL GALLERY. 
72 
for swimming, as are those of the second group. The zygoma is 
broad and powerful, in correlation with the; great development of 
the biting-muscles, and the lower jaw is articulated to the cranium 
by a closely fitting transverse hinge, which gives great strength and 
firmness to the joint, but entirely deprives the animal of the power 
of moving this jaw backwards and forwards, or from side to side, its 
only motion being in a vertical direction. The varied and highly- 
developed dentition diff’ers from that of other Mammals by the 
development of the last premolar of the upper jaw and the first 
molar in the lower into the so-called “ sectorial teeth, which are 
specially adapted for cutting up animal food. The shape of these 
teeth is highly characteristic of the different genera. 
[Case 4.] The Cats, or Felidce (Case 4, Divs. A to D), the most highly 
developed of the Carnivores, have unusually long and powerful 
canine teeth, admirably suited for seizing and killing their prey, 
and sharp-edged scissor-like sectorial teeth, equally well adapted 
for cutting up flesh or breaking and crushing bones, which form 
an essential part of their food. The actual number of teeth, 
however, is much reduced, the dental formula being I.|, C. |, 
Fig. 31. 
Fones of toe of Cat. A, with retracted, and E, Avitli extended claw. 
a, tendon of extensor muscle; h, retractor ligament; me, metacarpal; 
ph (1, 2, and 3), 1st, 2nd, and 3rd phalanges; s, bony sheath, into 
which the claw \s fixed. 
Pm. 3^ ]\I. -[ X 2=30; and the whole jaw is shorter in comparison 
with the length of the head, and therefore proportionally stronger. 
