PHALANGISTID^. 251 



gistidce we find certain modifications Loth 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, arid 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 Phalangista* 

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

 we have the genus Phascolarctos> 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, J:; false molars, \\\ ; true 

 molars, |;|. 



SIDE VIEW OF TEETH OF UPPER AND LOWER JAW OF A 



RC K.CIKS OK J'haldfiyte'lu. 



The anterior pair of incisors of the upper jaw are 

 longer than the rest, separated at the base, and meet 



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

 by Larepede. 



