1242 



THE RODENTS 



SKELETON OF SQUIRREL. 



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 characterized 

 by the zygomatic or cheek-arch of the 

 skull being slender, and mainly formed 

 by the jugale or cheek bone itself.* These 

 distinctive characteristics, which are 

 somewhat 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. 

 The African flying squirrels (Anomalurus] are distinguished from the true 



flying squirrels by the parachute-like membrane running along the sides of the 



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 Equatoria, while 



another is found on the east 



coast near Zanzibar. The ful- THE FULGENT AFRICAN FLYING SQUIRREL. 



gent flying squirrel (A.fulgens} 



from the Gabun is one of the largest species, measuring twenty-one inches in total 



length, of which a third is occupied by the tail; its color is bright tawny orange, 



* In 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. 



