SQUIRRELS. 
69 
jaw! taking its origin from the root of the sheath of the incisor tooth. The 
squirrel-like Rodents are especially distinguished by having the two bones of the 
lower leg (tibia and fibula), as shown in 
the accompanying figure of the skeleton 
of the squirrel, quite distinct from one 
another. They are further characterised 
by the zygomatic or cheek-arch of the 
skull being slender, and mainly formed 
by the jugale or cheek-bone itself.” These 
distinetive characters, which are some- 
what difficult for those not versed in 
anatomy to understand, may appear 
trivial and unimportant; but the fact is 
that all Rodents are so alike in general 
structure, that it is only by such slight 
points of difference that the various 
groups can be satisfactorily distin- 
guished from one another. 

SKELETON OF SQUIRREL, 
The African flying squirrels (Anomalurus) are distinguished from the true 
flying squirrels by the parachute-like membrane running along the sides of the 

THE FULGENT AFRICAN FLYING SQUIRREL. 
body being supported in front by 
a rod of bony cartilage arising 
from the elbow-joint (instead of 
from the wrist); and also by the 
presence of a row of overlapping 
horny scales on the under surface 
of the root of the long and 
thickly-haired tail. Their skulls 
also differ from those of the true 
squirrels by the absence of a bony 
projection from the frontal bones 
defining the hinder border of the 
socket of the eye. They have, 
moreover, but a single pair of 
premolar teeth in each jaw. 
Most of these flying squirrels 
are confined to Western Africa, 
but one species (A. pusillus) 
occurs in Kquatoria, while 
another is found on the east 
coast near Zanzibar. The fulgent 
flying-squirrel (A. fulgens), from 
the Gabun is one of the largest species, measuring 21 inches in total length, of 
1 This is the projecting process seen at the hinder extremity of the lower jaw in the skull figured on p. 66. 
2Tn the same figure the zygomatic arch is the bar of bone beneath the socket of the eye, of which the front 
portion is formed by the jugale or cheek-bone. 
