164 BULLETIN OF THE 
there were other species both smaller and larger. This animal was about 
eight feet high at the shoulder, and over twelve feet long. The height is 
greatly increased by the extraordinary development of the spines of the 
anterior dorsal vertebre. These are well preserved, and in two cases com- 
plete to the tip, in the materials at our disposal, They are broad and flattened 
nearly to the tip, so as to fit closely together. The neck is longer than that 
of Uintatheriwm, but shorter than that of the rhinoceros. With the power of 
flexing the elbow, the head could readily be lowered to the ground in feeding. 
The arm, fore-arm, and shoulder-blade are decidedly rhinocerotic in character, 
although showing a greater proportional length and less flexion capacity. 
The thigh and lower leg, on the other hand, are rather elephantine in their 
shape and proportions, and indicate much less play at the knee-joint than in 
the thinoceros. The limb bones are relatively shorter than in Uintatherium, 
but the metacarpals and tarsals are much longer and less spreading, thus 
adding considerably to the height. These segments, combined with the elonga- 
tion of the dorsal spines, gave Menodus as great a height as was attained by the 
eocene genus, with its longer limbs. 
AMYNODONTID. 
Rhinoceros-like animals, as far as yet known, extending from the Middle 
and Upper Eocene (Bridger Beds) to the White River Miocene Beds ; horn- 
less ; canines and incisors present in the typical number in both jaws ; pattern 
of the premolar transitional to that of the molars; first upper premolars rudi- 
mentary or wanting; pattern of true molars like that of the rhinoceros, but 
with the transverse crests simple; skull with a powerful sagittal crest. 
AMYNODON,* Marsh. 
Probable syn. Orthocynodon, Scott and Osborn.t 
Dentition: I. 8, C. 4, Pm. #, M. 3. Upper canines obliquely placed; lower 
canines erect and placed immediately in front of the upper when jaw is closed. 
The third and fourth upper premolars only approach the molar pattern by 
the development of double transverse crests. First upper premolar small and 
single fanged. Post-glenoid and post-tympanic processes separate. 
* This Eocene genus, owing to the imperfect condition of the type skull in Pro- 
fessor Marsh’s collection at the time of description, was incorrectly defined, (Am. 
Journ. Sci. and Arts, 3d Ser., Vol. XIV. p. 251,) and the present writers, after a 
personal examination, were led to believe that the type specimen of O. antiquus 
represented a distinct genus. It now proves to be the same, as far as we know at 
present. 
+ E. M. Museum Bulletin, No. 3, May, 1883. 
