BATS. 
81 
the radius [r), the ulna (u) being rudimentary. The thumb (px) is 
short, free from the flying-membranes, and provided with a claw 
{ph) ; while the other fingers are long, slender, and clawless, with 
the exception of the index, corresponding to our fore finger, which 
in some genera also possesses a claw. Clavicles {cl) are well 
developed in all the species. 
The hind limbs, on the other hand, are thin and feeble, and dif- 
ferent from those of all other mammals in that they are rotated 
backwards, so that the knee, like the elbow, is directed backwards. 
Those species which are provided with a flying-membrane between 
the hind legs have it supported by a long cartilaginous process or 
spur, which is attached to the heel. 
Bats are primarily divided into two groups, Frugivorous and 
Insectivorous. The members of the first are distinguished by their 
generally large size, large, smooth, and comparatively blunt teeth, 
well-developed postorbital processes, and by the presence of three 
phalanges to their index fingers. To this group belong the large 
Fruit-Bats or Flying Foxes {Pteropus), represented by the skeleton 
of Pteropus juhatus, and other genera, all of which live entirely 
on fruit, and are restricted to the Old World. 
The Bats of the insectivorous division are of small size, and have 
Skulls of (A) Noctule ( Vesperugo noctula) and (B) Blood-sucking Bat 
{Desmodus rufus). 
teeth covered with minute sharp-pointed cusps, as in the Insecti- 
vora ; they have no postorbital processes, and only one, or rarely 
two, phalanges in their index fingers. 
Fig. 40. 
A 
B 
G 
