1884.] Geology and Paleontology. 1035 
existing Ruminantia were derived from three lines represented by 
the genera Gelocus, for the typical forms, Poëbrotherium for the 
camels, and Hyæmoschus for the Tragulidz.” 
These views being then established on sufficient evidence, it 
remains to make such additions as the facts cited in the first part 
of this paper indicate. First in importance comes the place in the 
phylogeny of the Selenodonta, of the Oreodontida. The peculiar 
inward extension of the unciform bone already ascribed to them, 
characterizes also among extinct forms the genus Leptomeryx, 
and probably Hypertragulus. Among recent ruminants it is only 
seen in the Tragulide. If we arrange these types in serial order 
we find the modifications of forms to be generally identical with 
those cf the other ruminant lines, in the codssification of the 
bones of the legs and feet. This series may then be regarded as 
phylogenetic. The peculiar structure of the carpus of the Oreo- 
dontidæ puts them out of the question as ancestors of any type 
of existing ruminants other than the Tragulina. Whether they 
themselves can be traced to a five-lobed, or to a four-lobed buno- 
dont ancestor, remains an undecided question. It is not, however, 
probable that a five-lobed form has been intercalated in a series, 
both of whose extremities are four-lobed. If this be true, the 
Oreodontidæ must be regarded as an ancestral type of Seleno- 
donta, coéqual with the Hyopotamidz, and it may well be ques- 
tioned whether the latter can have been ancestors of the existing 
Ruminantia, whose molars are four-lobed. 
o the present investigation does not disclose the ancestral 
stock of the Pecora. In North America we have not progressed 
rther in the solution of this question than I reached in 1877; 
after a study of the genera Cosoryx Leidy, and Blastomeryx 
I had already* suggested that the former genus is the an- 
cestor of the Cervida, but subsequently* remarked “it is not prob- 
able that this genus is the immediate ancestor of Cervus, from the 
that the molar teeth display in their prismatic form a higher 
degree of specialization than belongs to that genus. It is prob- 
able that the true ancestor combined the dental type of Cervus 
the distinct roots and short crowns of the molars, with the 
type of horns here described.” I at that time included a species 
(Cosorye gemmifer Cope), in the genus provisionally, which has 
the type ing discovered another larger 
Species which has the same type of molars, I at once distinguished 
Blastomeryx, as a genus, and in describing the species ( B. bore- 
alis) observed as follows: “In brief, its molars differ from mre 
i Among Perissodactyles it occurs in Tapirus a ie PAEO 
$ Proceedings Amer, Philos. Soc., p. 223. 
oceed. Acad. Phil., 1874, p. 149. 
z Expl. and Surv. W. of rooth Merid. U. 
Ð. 
ft; i S., Geo, M. Wheeler in charge, 
7 pi. 349, 1877. 
