MAMMALIA, 529 
The ribs in the cat and dog form a compact thorax 
which, however, is remarkably narrow from side to side. 
The explanation of this peculiarity will be found in Chapter 
XXVI. (Sternum and Ribs). 
The limbs are fairly long and about equally developed. 
They resemble each other (dog and cat) far more closely 
than do those of the horse and ox. Both types are digiti- 
grade and unguiculate (little claws or unguicule on each 
toe). There are five toes in the front-limb and four in the 
hind, the hallux being the only aborted toe. In each the 
under-surface of the toes has a series of “pads” or callosities, 
consisting of a large middle one and a row of smaller ones. 
Coming to details, the scapula of the dog is slightly 
elongated, but broad, with about equal prescapular and 
postscapular fosse. It is distinctly a “transition” type. 
There is no clavicle, except for an occasional minute trace. 
The humerus is curved and there is a large supratrochlear 
foramen. The radius and ulna are both developed but 
immovably fixed together. The carpus has the scaphoid 
and lunare united to form one bone, the scapholunar (a 
carnivore feature), hence there are, with the pisiform, only 
seven carpal bones. The pollex is shorter than the other 
four toes and does not reach the ground. Hence the animal 
really walks on four toes in fore- and hind-limb. The last 
phalanges bear small blunt claws which are not retractile. 
In the hind-limb and girdle the pelvis is not unlike the 
ungulate type, but the ilium has not two “angles” or pro- 
cesses, as in the horse and ox, as the “angle of the croup” is 
very small. The femur is long and curved, the tibia and fibula 
are also proportionately long, and the latter is complete 
though thin. There is no reduction of the tarsal bones, and, 
as stated above, there are four functional toes. The hallux is 
often represented by a metatarsal bone, and may, as in the 
“dew-claw” of domestic dogs, be present as a small digit. 
The claws resemble those of the front-limb. In the cat 
there is a clavicle which is reduced in part and connected 
only by cartilage to the scapula and the sternum. The 
scapula has a metacromion barely present in the dog. The 
humerus is similar to that of the dog but proportionately 
longer. There is no supratrochlear foramen, but there is 
an entepicondylar foramen on the inner side. The radius 
M, 35 
