DENTITION. 229 



edges (machcerides) rise but very little in relief above tlie 

 ivory and cement. The ridge-plates are vertical and enor- 

 mously high, the fourteenth, which in the germ was not the 

 highest, measuring between 10*5 and 11 inches. The five 

 hinder plates fall off very rapidly in height. The crown is 

 very broad, being but a line or two short of five inches. 

 The following are the principal dimensions : — 



Length of crown measured by a tape, over the summit from base of talon to 

 anterior fang-pit, 18 - 25 in. Ditto from hind talon to anterior fang, straight by 

 callipers, 14 - 2 in. Width of crown in front, 3 - 4 in. Ditto at middle of ninth 

 ridge, 5 - in. Ditto behind, 3 - 5 in. Height of fourteenth ridge, 10 - 7 in. 



The ridges are so condensed that the joint length of the 

 posterior twelve, having worn discs, amounts only to 6 - 7 

 inches, being an average of about half an inch to each. The 

 Alabama tooth and this Texan molar agree in being of very 

 large size ; but they differ throughout in the detail of dis- 

 tinctive characters. I can detect nothing by which the latter 

 can be distinguished from E. primigenius. It is of a colossal 

 size. The substance of the bone and tooth is like iron-shot, 

 and the matrix is a coarse ferruginous gritty sand, mixed 

 with fine gravel. 



The second case is more remarkable and important, being 

 that of the fossil Elephant of the Pliocene Fauna of Mobrara, 

 an affluent of the Missouri River in Nebraska, the account of 

 which, by Dr. Leidy, has excited much interest and surprise 

 among palaeontologists. 1 According to that distinguished 

 naturalist, this extinct Fauna has already yielded 3 distinct 

 Canidce ; 3 distinct Felidce ; 2 Rodents ; 8 Ruminants, the ma- 

 jority of them new ; 8 Equidce, belonging to six genera or 

 sub-genera ; 1 large Rhinoceros (R. crassus, Leid.) ' which 

 appears to have had almost the same size and formula of 

 dentition as the recent Indian Rhinoceros, R. Indicus'; 1 

 Mastodon of the sub-genus Tetralophodon, M. mirificus, Leidy, 

 and a huge Elephant, E. (Eueleph.) imperator, Leidy. The 

 published descriptive details of this Elephant are as yet but 

 very meagre. One specimen only is mentioned, being the 

 anterior portion of an upper molar, of larger dimensions than 

 any known to the author. The crown is stated to be ' within 

 a line or two of five inches in breadth, and within a space of 

 seven inches only eight enamel-folds or double plates exist.' 

 This would give an average of nearly nine-tenths of an inch 

 to each ridge, corresponding closely with the proportions 

 yielded by E. Columbi. The ridges are described as becom- 

 ing worn into transverse strongly crenulated ellipses. Dr. 

 Leidy adds, ' that the fragment of the tooth has been 



1 Proceed. Acad. Nat. Scien. Philadelph. 1858, p. 20, et seq. 



