296 Frof> 0. C. Marsh — American Jurassic Mammals. 



writer, in the American Journal of Science. One figure, at least, of 

 a typical form of each new genus proposed, has also been given, 

 either in the original description, or in the present article. 

 The list is as follows : — 



Plagiaulacid^. 



Allodon laticeps. Amer. Journ. Sci., vol. xxi. p. 511, 1881. 



,, fortis. ,, ,, ,, xxxiii. p. 331, 1887. 



Ctenacodon serratus, ,, ,, ,, xviii. p. 396, 1879. 



,, nanus. ,, ,, „ xxi. p. 512, 1881. 



,, potens. ,, ,, ,, xxxiii. p. 333, 1887. 



Dryolestid^. 



Dryolestes prisms. Amer. Journ. Sci. vol. xv. p. 459, 1878. 



„ vorax. „ ,, ,, xviii. p. 215, 1879. 



,, arcuatus. „ ,, ,, xviii. p. 397, 1879. 



,, obttisus. „ ,, ,, XX. p. 237, 1880. 



„ gracilis. ,, ,, „ xxi. p. 513, 1881. 



Sty laeodon gracilis. „ ,, ,, xviii. p. 60, 1879. 



,, validus. „ „ ,, XX. p. 236, 1880. 



Asthenodon segnis. „ ,, ,, xxxiii. p. 336, 1887. 



Laodon venusius. „ ,, „ xxxiii. p. 337, 1887. 



DiPLOCYNODONTIDjE. 



Diplocynodon victor. Amer. Journ. Sci. vol. xx. p. 235, 1880. 

 Docodon striatus. „ ,, ,, xxi. p. 512, 1881. 



JEnneodon crassus. ,, „ ,, xxxiii. p. 339, 1887. 



,, affinis. ,, ,, ,, xxxiii. p. 339, 1887. 



Spalacotheeidje. 

 Menacodon rarus. Amer. Journ. Sci. vol. xxxiii. p. 340, 1887. 



TiNODONTIDJE. 



Tinodon bellus. Amer. Journ. Sci. vol. xviii. p. 216, 1879. 

 „ robustus. „ „ ,, xviii. p. 397, 1879. 



,, lepidus. ,, ,, ,, xviii. p. 398, 1879. 



TrICONODONTIDjE. 



Triconodon bisuUus. Amer. Journ. Sci. vol. xx. p. 237, 1880. 

 Friacodon ferox. „ ,, ,, xxxiii. p. 341, 1887. 



{Tinodon ferox). „ „ ,, xx. p. 236, 1880. 



Paurodontidje. 

 Paurodon valens. Amer. Journ. Sci. vol. xxxiii. p. 342, 1887. 



Nearly all the mammals older than the Tertiary, judging from 

 their dentition alone, miay have lived mainly upon insects, with 

 such accessory diet as modern Insectivores affect. The Plagiaula- 

 cidcB, however, shoW evidence of marked adaptation to some peculiar 

 food, whether animal or vegetable cannot yet be determined with 

 certainty. Now that the upper teeth of Ctenacodon are known, and 

 trenchant teeth are found opposed to the lower cutting premolars, 

 and tubercular molars to those below, the problem is simplified, but 

 not solved. The evidence at present points to an animal, rather 

 than to a vegetable, diet for all the Allotheria. 



It is not improbable that there was a gradual change in diet in 

 the later forms, until vegetable food predominated. The fact that 

 the Tertiary genus Neoplagiaulax, Lemoine, has only a single lower 



