337 



They, however, present an external character to easily recognisable, and influencing M I 

 rially the locomotive faculties, M to claim for it more consideration than thr modification of 

 the digits or premolars. A fold of the skin is extended on each tide of the body between 

 the fore and hind leg*, which, when outstretched, forms a lateral wing or parachute, but 

 which, when fht legs are in the position for ordinary support or progression, is drawn close 

 to the tide of the animal by the elasticity of the subcutaneous cellular membrane, ami there 

 forms a mere tegumentary ridge. These delicate and beautiful Marsupials have been sepa- 

 rated genetically from the Phalangers under the name of I'rtauru* : they further differ from 

 the Phalangers in wanting the prehensile character of the tail, which, in some Petaurists, ha* 

 a general clothing of long and soft hairs, whilst in others the hairs are arranged in two 

 lateral series. 



There is as little constancy in the exact formula of the dentition in the Petaurists, as among 

 the Phalangers. The Urgent species of IYtnuri.it (Pet. tayuanoidri), for example, is almost 

 identical in this respect with the PAalaayitta Coolrii, which M. Fr. Cuvier has therefore 

 classed with the Petauri. Those teeth of Pel. tayuanotdet which are .sufficiently developed, 

 and so equal in length, as to exercise the function of grinders, or, ill other words, the func- 

 tional series of molars, consist of six teeth on each side of the upper jaw, and fire teeth on 

 each side of the lower jaw. The four posterior molars in each row are true, and bear four 

 pyramidal cusps, excepting the last tooth in the upper jaw, which, as in Pk. Coolrii, lias only 

 three cusps. In the upper jaw the space between the functional false molar* and the incisors 

 is occupied by two simple rudimentary teeth, the anterior representing the canine ; but being 

 relatively smaller than in Pk. Cooicii, the crowns of the two anterior incisors are relatively 

 larger. In the lower jaw the sloping alveolar surface between the functional molars and huge 

 procumbent incisors is occupied by two rudimentary minute teeth. 



Purchatti. 



Genus Phalanyita. 



1851. The skeleton of the Vulpine Phalanger (l*hnlanyt*ln vulpina). 



The spinous processes of the third to the sixth ccrricals inclusive are almost obsolete. The 

 inner oondyle of the humcrus is perforated. The patella has not been ossified. The second 

 and third toes are extremely slender, and in the recent animal are inclosed in a common 

 sheath of integument as far as the claw*, a structure which has suggested the name of the 

 genus. The transverse processes of the 7 cervical* are perforated : 13 vertebrae are dorsal, 

 (i lumbar, and 2 sacral : '22 caudal vertebra* are preserved, and of these the second to the 

 eighteenth inclusive bear hsema|K>physe*. 



Mtu. Brooicei. 



1352. The skull of the Vulpine Phalanger (Phdanguta vulpina). 



A small detached prcmolar is preserved on the right side of the upper jaw, and there are 

 two rudiments! canines in the lower jaw : in other respects the dental formula is the same aa 

 in the Koala and Ilyptiprymnu*. 



Pretexted by Henry CKe, Etq. 

 II 



