524 FLYING FOXES CHAP. 
of the vertebrae tend to become ankylosed in old individuals ; 
the caudals have no processes, but are like those quite at the end 
of the series in long-tailed animals. The sternum is keeled for 
the better attachment of the pectoral muscles, the chief muscles 
of flight. The ribs, which are much flattened, are occasionally 
ankylosed together by their margins. There is a well-developed 
clavicle. In the carpus the scaphoid, lunar, and cuneiform are 
all fused together. In the hind-limb the fibula is rarely fully 
developed. 
The Bats are divisible into two primary groups, which are 
those of the Megachiroptera and the Microchiroptera. 
SuB-ORDER 1. MEGACHIROPTERA. 
The Pteropodidae are frugivorous Bats, usually of large size. 
The chief distinguishing feature is the fact that the molars 
are not tubercular, but marked with a longitudinal furrow, — 
which is, however, concealed in the genus Pteralopex by cusps. 
The palate is continued back behind the molars. The index 
finger has three phalanges, and is usually clawed. The ears 
Fic. 256.—Skull of Pteropus fuscus. x. (After de Blainville.) 
are oval, and the two edges are in contact at the base of the 
ear. The tail, if present, has nothing to do with the inter- 
femoral membrane. This group is entirely Old World in range. 
The genus Pteropus embraces the creatures known as Flying Foxes. 
They are the largest forms in the sub-order, sometimes having 
an expanse of wing of 5 feet (this is the case with P. edulis). 
The muzzle is long, and the face therefore “foxy ” in appearance. 
