396 MARSUPIALS. 



is but a very feeble indication of that median basal connecting ridge 

 which forms so characteristic a feature of the molars of the Kangaroo. 

 The two fangs are long, and the surfaces which are turned towards 

 each other are impressed by a longitudinal groove, as in the Tapir, 

 Dinothere, and Kangaroo. The molars progressively increase in 

 size from the first to the last : in a jaw, the symphysis of which 

 anterior to the molar series is four inches, the narrow toothless 

 margin between the incisor and the first molar is eight inches in 

 extent : the series of five molars occupies an extent of from ten 

 to eleven inches. The enamel of both molars and incisors is re- 

 markable for its reticulate and punctate exterior, as if worm-eaten ; 

 the holes being seen at the fractured margins of the enamel to lead 

 to smooth pits in that substance. 



156. Nototherium. — A second genus of large Pachydermoid 

 Marsupial has molar teeth resembUng in form, mode of implantation, 

 and relative size, those of the preceding genus, Diprotodon, but 

 apparently four in number on each side of the lower jaw, and 

 their crowns covered with smooth enamel ;(1) the Nototherium is 

 more especially distinguished by the total absence of incisors in the 

 lower jaw, and the much smaller size of the symphysis. 



Like the Diprotodon the Notothere had no canines, and being 

 also devoid of defensive tusks, I have called one species Nototherium 

 inerme. In a ramus of the lower jaw of this species, twelve inches 

 in length, the series of four molars, which commences within two 

 inches of the anterior end of the jaw is six inches in extent ; 

 the antero -posterior diameter of the last tooth is one inch nine 

 lines, and is situated internal to the base of the coronoid process. 

 In a rather larger species the Nototherium Mitchelli, the last molar 

 tooth is in advance of the base of the coronoid. 



1.57. Structure. — The dentine, enamel, and cement of the teeth 

 of the Marsupial animals present the usual microscopic characters 

 of these tissues in the Mammalia. 



The dentinal tubuli of the small molars of the Phascogale, 

 Myrmecobius, and Petaurus have very short trunks, and are rela- 

 tively larger and fewer in number as compared with the size of 



(1) PI. 91, fig. 4. 



