29 



UlNTATHERIUM LACUSTRE. Marsh. 



Dinoceras lacustris, Marsh, 1. c. October, 1872. (Published September 

 27th, 1872.) 



I have several of the teeth and the occipital, parietal and other por- 

 tions of the cranium of this species. It is distinguished from its con- 

 geners, apart from its smaller size, by the large size of teeth. These are 

 nearly as large as those of Loxolophodon cornutus, and considerably larger 

 than those of U. robustum and U. mirabile. The occipital condyles are 

 not larger than those of the Elk, Cervus canadensis. The mastoid pro- 

 tuberance is prominent, and the post-glenoid process more produced 

 downwards and with less fore and aft diameter than in the other three 

 species. The inferior temporal ridge is strongly marked, and the pos- 

 terior condyloid foramen is large. 



The posterior molar has a wide floor extending from the posterior or 

 straight transverse crest to the cingulum. This crest is low and has a 

 low tubercle near its apex behind. The other molars have strong fore 

 and aft cingula but none at ends. The worn surfaces are first V-shaped, 

 later arrow-shaped. The first premolar has curved outer crest and inner 

 conic tubercle. 



Measurements. 



M. 



Diameter of occipital foramen and condyles 092 



From exterior end condyle to mastoid 058 



" " " " to post-glenoid process 080 



Transverse diameter last upper molar 045 



" " third premolar 029 



Length molar series 163 



Found by the writer in the Bridger formation of South Bitter Creek, 

 Wyoming. 



MEGACERATOPS. Leidy. 



Proceedings Academy Natural Sciences, 1870, p. 1. Hayden's Geo- 

 logical Survey, Wyoming, 1872, 352 ("Megacerops"). 



This genus is only known from the extremity of the nasal bones bear- 

 ing the horn-cores. The latter are intermediate in position to the nasal 

 and naso-maxillary horns of Eobasileus, etc., and may represent the 

 median pair, in which case, the diagnosis of the genus should be, nasal 

 horn-cores wanting. 



The genus was originally regarded by Dr. Leidy as allied to Sivatheriitm 

 and therefore Ruminant ; he also supposed that it possessed a proboscis 

 "as in the tapir." The latter proposition has much in its favor, especi- 

 ally as the affinities of the genus are evidently with the Proboscidia. 



MEGACERATOPS COLORADOENSIS. Leidy. 

 Megacerops Coloradoensis. Leidy, i. c. 

 The part of this species preserved, indicates an animal of the size of 



