154 The American Naturalist. [March, 
posterior cingular cusp, is dedicated to Mr. T. C. Weston, the 
explorer of the region from which these fossils were obtained. 
Aceratherium mite Cope, 1. c. 
Aceratherinm pumiluni Cope, 1. c. 
Artiodactyla. 
Hypertragulus transversus sp. nov. 
Indicated by two superior molar teeth of old individuals. 
They are of nearly twice the linear dimensions of the only 
known species, H. calcaratus Cope. The external cusps are 
subconical, and the external rib which separates them in Lep- 
tomeryx is wanting here. Anterior cingular cusp small. The 
anterior bone of the posterior internal crescent enters the 
notch between the external cusps but does not fuse with either 
of them. Slight cingula on the anterior and posterior sides of 
the internal lobes which do not pass round their internal sides. 
No external cingulum. Diameters, anteroposterior, \2 mm.; 
transverse (at base) 15 mm. Crown very brachyodont. 
Leptomeryx esulcatus sp. nov. 
A single superior molar indicates this species, which is of 
about the dimensions of the L. evansii. It differs distinctly 
from this Tragulid, in the greater convexity of the external 
face of the external cusps, and the absence of the sulci which 
define an external median rib of that surface in the Z. evansii. 
The rib which bounds the external faces of the cusps from 
each other is present. Anterior external cingular cusp small, 
continuous with anterior cingulum. No internal nor external 
cingulum. Diameters of crown; anteroposterior, 6.5 mm., 
Leptomeryx mammifer Cope, Report, G. N. H. Survey, 
Canada, 1885, C p. 84. 
Four superior molars add to the characters already derived 
from mandibular teeth as above cited. The median and an- 
terior external cingular cusps are large and obtusely subconi- 
cal. The anterior external cusp has a very strong median 
external rib, while the posterior has a very weak one. The 
anterior horns of the internal crescents are much produced ; the 
posterior but little. The cingula are slight, and are not con- 
tinued round the internal base. Diameters of superior molar; 
anteroposterior, 11 mm.; transverse, 11.5 mm. 
Leptomeryx semicinctus sp. nov. 
A large species possessing twice the linear dimensions of the 
L. evansii in the superior molar teeth, is represented by three 
