DAKOTA AND NEBRASKA. 255 



Elephant, from its greater size, the comparative coarseness of the constituent 

 elements, together with the fact that it appeared to be a member of a peculiar fauna, 

 an associate of the Mastodon mirificus, as the ordinary E. americanus was of the M. 

 americanus. The notice oi EAmperator was published in a short "Notice of Remains 

 of Extinct Vertebrata from the Niobrara River," in the Proceedings of this Academy 

 for 1848, and before I had seen Dr. Falconer's paper "On the Species of Mastodon 

 and Elephant," published the previous year in the Quarterly Journal of the Geological 

 Society of London. 



The specimen assigned to E. imperaior is represented in figure 3, j)late XXV, 

 one-third the diameter of nature. It exhibits the characters attributed by Dr. 

 Falconer to E. Columhi, compared with the supposed American variety of E. 

 primigenms. 



The specimen is the fore part of an upper molar, probably the fifth. The tritu- 

 rating surface, extending the breadth of the fragment, is nearly five inches at its 

 widest part. The breadth on the less broken side is about seven and a half inches, 

 and contains only as many ridges, — that is to say, one ridge to an inch of breadth. 

 There is, however, a thick talon in front, and the ridges curve considerably backward 

 on the less broken side of the tooth. The four more perfect ridges of the specimen 

 at the middle of the triturating surface occupy a space of a little over three inches, 

 including the three intermediate plates of cementum. The widest ridges measure 

 four and a half inches. The enamel is thick and strongly crimped, and the den- 

 tinal tracts are slightly dilated at their middle. 



Elephas imperator, if not regarded as a peculiar species of a peculiar fauna, may be 

 viewed, together with those teeth which have been referred to E. Columhi, as belong- 

 ing to the Elephas americanus. 



Other remains of Elephants, as Dr. Hayden supposes them to be, he observed in 

 association with those o? Mastodon mirificus, Equus excelsus, and Hipparicm, at the 

 head of the Loup Fork branch of the Platte River, also between this point and the 

 Niobrara River, and on the latter. 



In a recent visit to Washington, I observed in the Geological Cabinet of the General 

 Land Office a penultimate inferior molar of an Elephant, obtained by Dr. Hayden in 

 Johnson Co., Nebraska. The tooth is of the coarse-plated variety, and its breadth 

 was about one foot. The triturating surface had an extent of eight inches, and ex- 

 hibited nine worn lobes. Behind the latter there were four unworn lobes and a 

 rudiment of another. 



More recently I have had the opportunity of inspecting some remains of an 

 Elephant from Talbot Co., Maryland, in the possession of Prof. E. D. Cope. They 

 indicate an animal approaching mature age. Among the remains are four molars, 

 apparently the last of the temporary series from both jaws. They are well worn 



