1914] Buwalda: A Proboscidean Tooth from Western Nevada 307 



been obtained from the Oregon beds. King correlated the Truckee, 

 therefore, with supposed Miocene, which is now considered as 

 Oligocene. 



It is obvious that the three lines of evidence of the King survey 

 above mentioned, i.e., the rhinoceros tooth, the fresh-water molluscs, 

 and the presumed continuity with supposed Miocene deposits several 

 hundred miles away which are now recognized as Oligocene, are rather 

 inconclusive as to the age of the Truckee. The writer is not aware 

 of other definite palaeontologic or stratigraphic evidence having been 

 adduced as to the age of the Truckee subsequent to the publication 

 of the reports of the King survey. 



The proboscidean tooth obtained by the writer is the posterior part 

 of a cheek-tooth, showing two transverse crests (figs, la and 16). The 



Figs, la and 1&. Tetrabetodon(?) , sp. Cheek-tooth. No. 21679, X Fig. 

 la, occlusal view; fig. 1&, lateral view. Truckee beds near Verdi, Nevada. 



tooth is practically unworn. Each transverse crest consists of two 

 principal tubercles and one or two accessory tubercles. In that the 

 accessory tubercles are few in number, the tooth is of a relatively 

 simple type. The terminal crest is quite blunt ; the next one is com- 

 pressed anteroposteriorly and forms a high, sharp ridge. The 

 cingulum is not pronounced. The tubercles are somewhat roughened. 

 The length of the last transverse crest at the base, measured trans- 

 verse to the long axis of the tooth, is about 40 mm. ; length of second 

 crest at base, about 65 mm. The tooth is small compared with the 

 cheek-teeth of the Pliocene and Pleistocene mastodons. It is much 

 larger, however, than cheek-teeth representing Palaeomastodon. 



The specimen is probably too incomplete for specific determina- 

 tion. It certainly represents a proboscidean of the mastodon type 

 and probably of the Tetrabelodon group. Its value lies in the fact 



