what 
1886.] Geology and Paleontology. 369 
outward. The symphyseal suture is short and rather deep. 
Its posterior edge is below the posterior quarter of the third 
premolar. 
In 
the Merychyus pariogonus Cope of the Deep River Ticholep- 
tus bed, the posterior part of the ramus is more expanded, and 
is perfectly rounded, while the other dimensions are considerably 
smal 
Fu 
ler. 
ll descriptions of these species are given in a paper read 
before the American Philosophical Society, Feb. 19, 1886 
The species of the Ticholeptus beds of Montana are the fol- 
wing : 
lo 
Mastodon proavus Cope. . Cyelopidius emydinus Cope. 
Protohippus sejunctus Cope. Pithecistes brevifacies' Cope. 
Merycocherus montanus Cope. de decedens Cope. 
Merychyus zygomaticus Cope. i heterodon Cope. 
i4 pariogonus Cope. Procamelus vel Protolabis, sp. 
Cyclopidius simus Cope. Blastomeryx borealis Cope. 
The only species common to the two lists is the Blastomeryx 
borealis, a fact which indicates some important difference in the 
horizons, either topographical or epochal. The Oregon speci- 
mens 
with 
consist of teeth only, from both jaws, which are identical 
those of the three crania known from Deep river. This 
animal is one of the deer-antelope, with persistent horns and 
deer-like dentition. Its horns are long and stout, and have a 
wide 
basal expansion above the posterior part of each orbit. It 
is about as large as the black-tailed deer. 
The Ticholeptus horizon is interesting as that in which the 
genus Mastodon makes its first appearance in America. It is 
how shown to be the last which contains the genus Anchither- 
tum.— £, D. Cope 
numerous the number of known fossil ones given. In the — 
‘™yriopods American forms predominate, while among the Arach- 
nida more European species are known. The tables of geologi- ` ee 
the degeneracy and approaching extinction of this type, as I have remar d z ; 
sis of the Oreodontide, Proceedings American Philosophical Society, _ 
H 
25 
