Zooloyical Society. J 27 



portance, separated also, like the corresponding anterior false molar 

 in the Opossum, by a short interval from those behind. 



The canine tooth but slightly exceeds in size the above false 

 molar, and consequently here occurs the first great difference be- 

 tween the Phalangers and Opossums ; it is however, only a difference 

 in degree of development ; and in the Ursine and other Phalangers, 

 as well as in the Petaurists, the corresponding tooth presents more 

 of the proportions and form of a true canine. 



The incisors, which we have seen to be most variable in number 

 in the carnivorous section, are here three instead of five on each side, 

 in the upper jaw, but their size, especially that of the first, compen- 

 sates for their fewness. 



In the lower jaw, there is the same number of true molares and of 

 functional false molares, which form a continuous and tolerably equable 

 series, as in the Opossums, on each side ; then two very minute and 

 rudimental teeth on each side represent the small spurious molar, 

 and small canine of the upper jaw ; and anterior to these, there is one 

 very small and one very large and procumbent incisor on each side. 



The constant teeth in this group are the J^| true molares, and the 

 j^ incisors. The canines — are constant in regard to their pre- 

 sence, but variable in size ; they are always minute in the lower jaw. 

 With respect to the spurious molares, ~, they are always in contact 

 with the true grinders, and their crowns reach to the same grinding 

 level ; sometimes a second spurious molar is similarly developed as in 

 the Phal. Cookii, and as in all the flying Phalangers, or Petaurists, but 

 it is commonly absent or replaced by a very minute tooth, shaped 

 like a canine : so that between the posterior spurious grinder and 

 the incisors we may find three teeth, of which the posterior is the 

 largest, as in Phal. Cookii, or the smallest, as in Phal. cavifrons ; 

 or there may be only two teeth, as in Phal. ursina and Phal. 

 vulpina, and the species, whatever that may be, which Fr. Cuvier 

 has selected as the type of the dentition of this Genus. 



In the lower jaw similar varieties occur in these small and unim- 

 portant teeth ; e. g. there may be between the procumbent incisors 

 and the posterior false molar, either four teeth, as in Phal. Cookii ; or 

 three, as in Phal. cavifrons ; or two, as in Phal. ursina, Phal. ma- 

 culata, Phal. chrysorrhoos ; or lastly, one, as in Phal. vulpina, and 

 Phal. fuliginosa. 



The most important modification is presented by the little Phal. 

 gliriformis of Bell, which has only three true molares on each side of 

 each jaw. 



