1873.] 61 [Cope. 



generic characters may have been mentioned. He had previously applied 

 it without description to the Uintatherium anceps, Aug. 24th (and 19th*, 

 in an erratum, where Mastodon anceps is altered into Tinoceras anceps). 

 As no characters whatever were assigned to it on either of these occa- 

 sions, it had no value in zoological nomenclature, and must bear date 

 September 21st. Under date of September 27th, Prof. Marsh proposed 

 the name Dinoceras (American Journal Science Arts, 1872) for the XT. 

 mirabile, but did not give his reasons for separating it from his former 

 genus (the names of the two bear an objectionable resemblance), or 

 those published by Dr. Leidy, or myself. Until such reasons be adduced, 

 I retain it also in Uintatherium, as is done by Dr. Leidy. 



I am acquainted, by autopsy, with two species of this genus. Xone of 

 them are so large as the Eobasileus pressicorni* ; U robustum, Leidy, 

 is smaller, and the U. lacustre, Marsh, smaller still. XT. mirabile 

 (Dinoceras, Marsh) is about the size of the U. robustum, and nearly allied 

 to it ; but it may be distinct, as it has a larger mastoid process. Tinoceras 

 grandis, Marsh, agrees in measurements with the E. pressicomis, and is 

 perhaps that species or the E. furcatus. The Tinoceras anceps, Marsh, 

 has been so imperfectly characterized as to be practically unknown. It 

 is one of the smaller species, and is most likely to be identical with the 

 U. robustum, whose name it antedates. Until these points be cleared up, 

 I retain three species, as follows : Uintatherium robustum, Leidy ; U. 

 mirabile, Marsh ; U. lacustre, Marsh. For convenience I compare these 

 species with those of Eobasileus. 



The naso-maxillary horn-cores have been seen in E. pressicornis and XT. 

 mirabile, and the nasal tubercles in the same. The posterior horn-cores 

 are known in the XT. mirabile. The posterior and lateral crests of the 

 cranium inclose a basin-shaped concavity above in all these species ; it 

 has been observed in all but E. furcatus. The dentition is similar to 

 that in Loxolophodon, i.e., I. ; C. 1 ; P. M. i ; M. 2. The first premolar 

 in U. lacustre has an internal cone and outer concave crest. The 

 worn surfaces of the other teeth in that species, U. robustum and 

 XT. mirabile, are narrow ovate, with a deep exterior emargination. The 

 true molars support two crests, which converge inwards and unite with 

 a small tubercle behind the apex in U. lacustre and IT, robustum. The 

 tusk is long, compressed and double-edged, as in Loxolophodon. The 

 last inferior molar in XT. robustum possesses three transverse crests, the 

 posterior two parallel, and obliquely directed inwards towards the axis 

 of the anterior, which is the highest. 



In a specimen of one of the smaller species, the ulna widens consider- 

 ably distally, being nearly as wide as the olecranon. The latter is large, 

 flattened and subtransverse, and presents a sharp ridge internally. On 

 the inner side of the distal part of the articular face for the humerus is a 

 tubercle, from which a short, wide groove runs out on the inner face of 



* These papers were not received by me till early in December, 1872. 



