PHALANGISTID.E. 



251 



gistidoe we find certain modifications both in their 

 dentition and external characters, upon which genera, 

 and subgenera have been founded. They are divided 

 into three genera : those which have a large mem- 

 brane extended from the sides of the body, and joined 

 to the fore and hind-legs, as in the flying Squirrels, 

 and which enables them to sail in the air like a para- 

 chute (but not to fly) constitute the genus Petaurus. 

 To those which have no such membrane, and have 

 a prehensile tail, the generic term Vhalangista^ 

 (Geofroy Saint-Hilaire,)is now restricted; and thirdly, 

 we have the genus Phascclarctos^ containing only one 

 species, (the Koala) which is at once distinguished 

 by its want of tail. 



The constant teeth in the genus Phalangista are :— 

 Incisors, f:f; canines, l'.^; false molars, \\\; true 

 molars, f :|. 



SIDE VIEW OF TEETH OF UPPER AND LOWER JAW OF A 



SPsciEs OF Phalangista. 



The anterior pair of incisors of the upper jaw are 

 lon;:rer than the rest, separated at the base, and meet 



* The same group is called Balantia by Illiger, and Cuscus 

 ]^,y Lac-epe'de. 



