12 



Tribe III. CARPOPHAGA. 



Stomach simple ; caecum very long. 



In this family, the teeth, especially those at the anterior part of 

 the mouth, present considerable deviations from the previously de- 

 scribed formulae ; the chief of which is a predominating size of the 

 two anterior incisors, both in the upper and lower jaw. Hitherto 

 we have seen that the dentition in every genus has participated more 

 or less of a carnivorous character ; henceforth it will manifest a 

 tendency to the Rodent type. 



The Phalangers, so called from the phalanges of the second and 

 third digits of the hinder extremities being inclosed in a common 

 sheath of integument, have the innermost digit modified, to answer the 

 purposes of a thumb ; and the hinder hand being associated in many 

 of the species with a prehensile tail, they evidently, of all Fruyivora, 

 come nearest the arboreal species of the preceding section. In a sy- 

 stem framed on locomotive characters they would rank in the same 

 section with the Opossums. We have seen, however, that they dif- 

 fer from those Entomophagous Marsupials greatly in the condition 

 of the intestinal tube. Let us examine to what extent the dental 

 characters deviate from those of the Opossums. 



In the skull of a Phalangista Cookii, now before me, there are both 

 in the upper and lower jaw four true molares on each side, each beset 

 with four three-sided pyramidal sharp-pointed cusps ; thus these 

 essential and most constant teeth correspond in number with those 

 of the Opossum : but in the upper jaw they differ in the absence of 

 the internal cusp, which gives a triangular figure to the grinding sur- 

 face of the molares in the Opossum ; and the anterior single cusp is 

 wanting in the true molares of the lower jaw. 



Anterior to the grinders in the Phalanger, there are two spurious 

 molares, of similar shape and proportions to those in the Opossum ; 

 then a third spurious molar, too small to be of any functional im- 

 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 



uterine development in these Opossums. Since the marsupial bones serve 

 not, as is usually described, to support a pouch, but to aid in the function 

 of the mammary glands and testes, they of course are present in the skeleton 

 of these small pouchless Opossums, as in the more typical Marsupials. 



