K H. Barbour — New Longirostral Mastodon. 87 



Art. III. — A New Lonyirostral Mastodon, Tetrabelodon lullL 

 Preliminary Notice ; by Erwin II. Barbodr. 



During the field season of 1914, the Nebraska Geological 

 Survey, while exploring the Pliocene exposures along the 

 Minichaduza, Niobrara, and Snake rivers, in Cherry County, 

 obtained a new and unusual longirostral mastodon. It was 

 found near Burge in the deposits bordering a stream variously 

 termed Snake Creek and Snake Kiver. The latter name is 

 preferable since it avoids confusion with Snake Creek, and the 

 Snake Creek beds, in Sioux County. The beds around Burge 

 are equivalent to the well-known Snake Creek, and it might be 

 sufficiently distinctive, as well as associative, to call these 

 deposits the Snake Biver stage. 



The gradient of the streams at this point is rather steep, and 

 the land surfaces are well washed and gullied. There are bare 

 canyon walls of Loup Fork two hundred feet high, heavily 

 capped by sand hills. Large numbers of bones, mostly pro- 

 boscidean, have been more or less completely washed out. 

 Unfortunately the bulk of them are fragmentary. These 

 deposits might well be called the mastodon beds, because mas- 

 todon bones are found in such abundance for a distance of 

 almost two hundred miles. It should be explained, however, 

 that much of this area is deeply covered and obscured by sand. 



On one talus slope, the number of mastodon bones led the 

 party to explore the canyon walls well to the top. Here a 

 tusk and associated bones were found, together with the man- 

 dible shown in the accompanying figure. It is assumed that 

 these associated bones are related. Work will be resumed 

 later in this spot, and it is believed that the skull, missing 

 tusk, and other parts of this individual may be recovered. 



The mandible is uncommonly large, and remarkably well 

 preserved. Unfortunately the very tip of the rostrum, as well 

 as any tusks which it may have borne, are wanting. The 

 great length of the rostrum would, in itself, be sufficient to 

 warrant the assumption that inferior tusks were present in life. 

 The alveolus also suggests the probability of their presence, 

 although they must have been slim. Dr. Bichard S. Lull, who 

 examined this specimen, concurs in the belief that the mandible 

 probably bore tusks. 



We wish to propose the name, Tetrabelodon lidli, for this 

 new species ; in honor of Professor Bichard Swann Lull of 

 Peabody Museum, Yale University. It is probably entitled 

 to rank as a new subgenus. 



Measured from the condyle, the length of the mandible, as 

 found in the quarry, exclusive of tip and tusks, is 52 inches 



