584 GEOLOGICAL SURVEY OF THE TERRITORIES. 



Thus there is a ji^reat inequality in the height of the transverse crests of 

 the posterior ui)per molar, the anterior, or the arched one, rising to a 

 high cusp at its outer extremity. A small tubercle exists on the side 

 of the inner angle of the grinding surface in the penultimate molar. 

 The same angle is much elevated in an anterior molar. The canine is 

 wider distal iy than in L. cornutus, and less recurved. The mastoid 

 process is quite prominent. The humerus has a prominent internal 

 condyloid ridge and tuberosity, and the condyles are not very oblique. 

 The inner posterior lobe of the tibial face of the astragalus is quite well 

 defined ; there is no median ligamentous pit on the trochlear face. 



Measurements, (from Leidy.) 



Inches. 



Depth lower .jaw at last molar 3. 25 



Length humerus, about 21. 00 



Diameter at condyles 7. 50 



Found by Dr. J. V. Carter and Dr. Leidy, near Fort Bridger, Wyo- 

 ming. 



Dr. Leidy has suggested with some reason that this sj)ecies and the 

 Dinoceras mirahUis of Marsh are identical. 



UlNTATHERIUM MIRABILE, Marsh. 



Dinoceras mirabilis, Marsh, Amer. Journ. Sci. Arts, 1872, October, (published Sept. 27.) 



Loc. cit., Jan. 2i-!, 1873. 



The cranium of this species has been partially described as above 

 cited, and figures in the last-named jjaper largely supply the deficiency. 

 From this it is evident that it differs from Lo.rolophodon cornutus in the 

 generic characters already mentioned, and, further, in the anterior posi- 

 tion of the naso-maxillary horns, the ijerforation of the lachrymal, the 

 anterior development of the malar, the oblique occiput, &c. It differs 

 from the U. pressicornis, besides the inferior size, in the shorter nasal 

 bones and greater posterior approach of the premaxillary bones to the 

 base of the horns ; in the much shorter horns and greatl^' smaller part 

 taken in their composition by the nasals. 



Tliese differences account for the great number of errors committed by 

 Professor Marsh in his allusions to other species, especially LoxolopJwdon 

 cornutus described by me, (see his second article above quoted.) Ac- 

 cording to Marsh this species differs from U. robustum in the absence of 

 a small tubercle on the last molar, and presence of one on the penulti- 

 mate molar. 



Measurements, (from Marsh.) 



M. 



Length of cranium, (28.5 inches) 0.722 



Width over orbits 202 



Width between summits 7i<i so-maxillary cores I(j9 



Width between summits nasao-maxillary cores 038 



Height naso-maxillary cores, (3 inches) . 075 



Length canine (9.25 inches) below jaw 232 



Diameter fore aiul aft at base 064 



Diameter transverse at base 025 



Length of molar series 150 



Last superior molar series 036 



Unitatherium l^custre, Marsh. 



Dinoceras lacustris, Marsh, 1. c. October, 1872, (Published September 27, 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 cou- 



