TYPES OF MAMMALS. 
15 
tion of the fingers, the fore-limbs are converted into wings 
(fig. 1), supporting a web of skin stretched between them. 
3. A Sloth, in which the ends of all the limbs are reduced to 
mere hooks, by whose aid the creature hangs back-downwards 
from the boughs of the trees among which it passes its entire 
existence. 
4. The Baboon serves as an example of an animal walking 
on all four limbs in the "plantigrade" position, i.e., with the 
Fig. 1. — Skeleton of a Fox-Bat. 
c/, clavicle ; cv, cervical vertebrse ; d, dorsal vertebrsp ; fh, fibula; fm, femur 
7i, humerus; hx, great toe, or hallux ; I, lumbar vertebrse ; rnc, metacarpals ; 
mf, metatarsals ; ph, phalanges ; pv, pelvis ; px, thumb, or pollex ; r, radius ; 
s, sacral vertebrse ; so, scapula ; sk, skull ; th, tibia ; ts, tarsus ; u, ulna. 
whole of the palms of the hands and soles of the feet applied to 
the ground. 
5. A small species of Antelope shows the characteristic form 
of a running animal, in which the limbs perform no office but 
that of supporting the body on the ground. It stands on the 
tips of the toes of its elongated slender feet. 
6. A Porpoise, adapted solely for swimming in the water. 
The fore-limbs are converted into flattened paddles, and the 
