316 
A MEMOIR UPON THE GENUS 
Pal;eosyops valudens. 
This species has been described by Prof. Cope' from a lower jaw which was 
discovered in the Washakie Eocene. He also described a series of superior molars 
under the same name, but was doubtful whether they should be assigned to this 
species or not. I have shown elsewhere" that the latter specimens should be 
referred to Telmatotherium mlidus Marsh. I am uncertain whether P. vallidens 
should really hold a specific rank, as the characters of its molars are so closely 
related to those of Telmatotherium that it is difficult to separate it from the latter 
genus. At any rate it is one of the most interesting varieties or species of this sub- 
family that I have studied and is a true connecting form between Paleeosyops and 
Telmatothei'ium, thus showing how closely these two genera are related to each 
other. 
The diagnostic characters of this species are the posi- 
tion and form of the posterior tubercle of the last lower 
molar, which in this variety assumes the character of this 
lobe in P. paludostis ; but in other respects all the charac- 
ters of the teeth are really those of Telmatothermm. 
Dentition. — The teeth have high and elongated 
crowns such as we find in the genus Telniatother- 
mm. Their lobes and crests are very prominent, with 
sharp cutting surfaces. The molars are totally without 
external cingula. In the premolar series there is no well- 
marked diastema in the jaw under consideration, which 
would distinguish this species from T. hyognathus, although 
ithe total measurements of the molar series are about 
^ equal. 
The fii’st premolar is wanting in this jaw; the second 
has a very high protoconid, which exhibits the same differ- 
ence in size to the posterior cone that is seen in Tclniatother- 
'' hmi. The V’s of the last jjremolar are apparently not as highly 
developed as in the la.st named genus. The lobes of the two 
anterior true molars are very much abraided. The last infer- 
ior molar (fig. 4) is a very high crowned tooth, much elon- 
gated, with the valleys deeply bordered by prominent crests ; 
its posterior tubercle, instead of being a functional lobe as in 
Telmatotherm7n, is only a cone, without a median valley or 
lateral crests. In this respect this molar resembles that of 
P. paludos7is but difters from the latter in its posterior 
tubercle having a transverse diameter as great as the whole 
width of the tooth in front. Then again the last molar of this species shows its 
'Pal. Bull. No. 7, p. 1, Aug. 22nd, 1872. 
'Prelim. Obs. upon Palajosyops and allied genera. Proc. Acad. Nat. Sei. Phil., Jan., 18i)l. 
PAgukk 4.— a series of last 
inferior molars to sliow 
the form of the posterior 
tubercle. 1 . Palico.<ti/op.‘t pal- 
•udoma. 2 . Pal!cosyop.f pal- 
udoKHis, variety. S. Palico- 
syopn vallidens. 4 . Telmato- 
thrrimn cuUridens. Two 
thirds natural size. 
