SQUIRRELS. 



69 



SKELETON OF SQUIRREL. 



jaw 1 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. 2 These 



distinctive 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. 



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 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. 



2 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. 



THE FULGENT AFRICAN FLYING SQUIRREL. 



