134 



Zoological Society, 



ones are also traversed by an internal longitudinal groove, but 

 this is so deep and wide, that it divides the vi^hole tooth into two 

 prismatic portions, with one of the angles directed inwards. The 

 inferior molares are in like manner divided into two trihedral portions, 

 but the intervening groove is here external, and one of the faces of 

 each prism is turned inwards. All the grinders are curved, and de- 

 scribe about a quarter of a circle ; in the upper jaw the concavity 

 of the curve is directed outwards, in the lower jaw inwards. The 

 false and true molares like the incisors have persistent pulps, and are 

 consequently devoid of true fangs : in which respect the Wombat 

 differs from all other Marsupials, and resembles the extinct Toxodon, 

 the dentigerous Bruta, and herbivorous Rodentia. 



Although none of the Marsupialia possess teeth composed of an 

 intermixture of layers of ivory, cement and enamel through the body 

 of the crown ; yet the layer of cement which covers the enameled 

 crown is thickest in the vegetable-feeding Marsupials, and is re- 

 markably distinct in the Wombat. .] 



I may add that the Wombat deviates from t^e other Marsupials 

 in the number of its ribs : as these are very constant in the rest of 

 the order, the difference in the Wombat, which has 15 pairs, in- 

 stead of 13 or 12, is the more deserving of notice. The Koala, like 

 the Phalangers and Kangaroos, has 13 pairs of ribs. 



Professor Owen next proceeds to compare the classification of the 

 Marsupialia here proposed with that of Cuvier, given in the second 

 edition of the Regne Animal, and states the reasons which have led 

 him to devise a new arrangement. 



The following is a tabular view of Professor Owen's classifica- 

 tion. 



CLASSIFICATION OF 



Families. 



Tribes. 



Sarcophaga. 



Three kinds of teeth; 

 canines long in both 

 jaws ; a simple sto- 

 mach ; no intestinum 

 ceecum. 



Extinct transitional forms 



Entomophaga. 



Three kinds of teeth in 

 both jaws ; a simple 

 stomach ; a moderately 

 long intestinum ctBcum. 



Dasyuridee. 



THE MARSUPIALIA. 



Genera. Subgenera, 



r Thylacinus, 

 ■< Dasyurus. 

 y Phascogale. 



J Phascolotherium 

 \ Thylacotherium 



':} 



FossiL 



Amhulatoria. . Myrmecobihs. 



Saltatoria. 

 Scansoria. 



r Chaeropus. 



\ Perameles. 



Didelphis. 



Cheironectes. 



