HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 227 
Synonym: M. parvus Barbour, Nebraska Geol. Survey, Vol. III, pt. 3, p. 222 
(1909). 
Type: Portions of skulls, a series of cervical vertebrae, a series of anterior and 
posterior dorsals and lumbars, fore limb and manus, hind limb and pes, repre- 
senting different individuals, and bearing the following numbers in the Catalog 
of Vertebrate Fossils in the Carnegie Museum: No. 1707, 17034, B, and 
C, 1700, and 1701. 
Paratype: Upper posterior portion of a cranium belonging to Mr. Harold Cook’s 
Collection, No. 133. 
There is a considerable quantity of other fragmentary remains of this species, 
besides those upon which the original description was based, which are contained 
in the Carnegie Museum. 
Geological Horizon: Lower Harrison Beds, Nebraska (Lower Miocene). 
Specific Characters: Supra-orbital ridges well separated revealing a broad smooth 
area between them, and not tending to unite to form a sagittal crest near the 
occiput; interparietal subquadrate in outline; cervical vertebre relatively 
light; transverse process of fifteenth dorsal simple, not pierced by a foramen; 
the transition between the posterior dorsals and anterior lumbars marked 
by a less abrupt change in the form of the zygapophyses of the latter than 
is the case in M. elatus; neural spines of the lumbars and sacrals having a 
comparatively greater backward slope than in M. elatus; limbs and feet rela- 
tively light; scapula narrow and long; size approximately that of a tapir. 
The material secured in the openings made in Carnegie Hill representing the 
genus Moropus consists of the remains of a number of individuals of large size, 
which it is possible in the light of Professor Marsh’s types to unhesitatingly refer 
to Moropus elatus Marsh, as has already been pointed out. Associated with this 
material there are remains, some of which undoubtedly represent smaller and less 
mature individuals of the same species. There is also a quantity of material, some 
of it representing undoubtedly immature individuals, but a great deal of it repre- 
senting fully adult individuals, which differs widely in many particulars from that 
representing M. elatus. 
Three hypotheses have been proposed and discussed in all their bearings: 
(1) that this material may represent immature specimens of M. elatus; (2) that it 
may represent the female sex of M. elatus; (3) that it may represent a species 
different from M. elatus. 
1. First Hypothesis.—In favor of this hypothesis is the fact that the specimens 
are smaller in size and that a few of them through the loss of the epiphyses of the 
