pretty evident that Thylacoleo, with its three upper incisors, could 

 not have been derived from Trityhdon, in which there are only two 

 of these teeth ; the same remark being also applicable in the case of 

 the Macropodidce. 



Genus TRITYLODON, Owen \ 



Syn. Triglyplms, Fraas 2 . 



Dentition: I.?, 0. f, Pm.|, M. p The diastema is of great 

 length, the first upper incisor is large and scalpriform, and the 

 second small and functionless ; each ridge of the upper cheek-teeth 

 usually carries three subconical tubercles. 



Fig. 33. 



Trityhdon fraasi, n. sp. Lyd. Upper molar ; from the Triassic bone-bed near 

 Strasbourg. The central figures are of the natural size, the others f . (From 

 the ' Neues Jahrb.') 



The upper molar from the Triassie bone-bed near Strasbourg (fig. 

 33), figured by Fraas under the name of Triylyplms, presents no 

 characters by which it can be generically distinguished 3 from Trity- 

 lodon, and may therefore be at least provisionally referred to that 

 genus ; but as its smaller size 4 indicates its specific distiuction, it 

 may be named T. fraasi. 



Tritylodon longsevus, Owen 5 . 



This is the type species, and appears to have been somewhat 

 smaller than a Uadger. 

 Hob. South Africa. 



1 Quart. Journ. Geol. Soc. vox. xl. p. 146 (1884). 



2 ' Vor der Sundfluth,' p. 215 (Stuttgart, 18(56). The name is preoccupied for 

 a genus of Diptera. 



3 The character mentioned by Neuinayr, Neues Jahrb. 1884, vol. i. p. 279, 

 cannot be regarded as of more than specific value. 



4 It is of too large dimensions to have been the tipper molar of Microlestes, 

 which was probably two-ridged. Loc. cit. 



