1881.] 495 
[Cope. 
Measurements. M. 
Diameters of base Pan, iit oa geeieas noe S006 
tYANSVEYSE. ....... 2. eee .007 
ee of tase Pau. Iv anteroposterior ........... .008 
; tYANSVEYSC....... 0000 c eee .010 
os of base of M. IL anteroposterior .........., .011 
: transverse......... Shurae - .018 
i vertical.......... 005 
“s inferior P-m. III (or IV) < anteroposterior... .007 
transverse. ....... .005 
Depth of ramus at same tooth........ Stites ox we. .012 
Thickness ramus at succeeding tooth......... auherne toy 009 
The Meniscotherium terrerubre differs from the M. chamense in two 
features. The first is its superior size. The second is the flattened form 
of the external faces of the true molars and the absence of the convexity 
of the external bases of the crown. 
My specimen of this species is from the red Eocene bed in Northwestern 
New Mexico, from the true Wasatch horizon, or higher than that which 
produced the other species here described. It was found by my assistant, 
D. Baldwin. 
REMARES. 
As stated in my report to Lieut. Wheeler in 1877, no vertebrate remains 
had been found in the Puerco beds, which underlie the Wasatch in New 
Mexico, up to that time. It was therefore uncertain whether they form 
the top of the Cretaceous or the bottom of the Tertiary series. I have 
recently obtained evidence of the existence of Champsosaurus in them, so 
that their position might be supposed to be in the Postcretaceous system. 
It is however quite possible that the species of Mammalia described in 
this paper were derived from the Puerco Formation. Their horizon is be- 
Jow the Wasatch, and they represent a different fauna from that of those 
beds. 
Attention has already been directed to this fauna in the pages of the Amer- 
tcan Naturalist.* I have recorded the presence of the Creodont genera, 
Periptychus, Triisodon and Deltatherium, and of the saurian Champ- 
sosaurus. I have now added the genera Hyracotherium and Meniscotherium, 
and a number of new forms of considerable interest. These are the Creo- 
dont Mesonyzx, a new genus allied to Hsthonyz, and a series of genera and 
species with a suilline type of dentition, but whose affinities are by no 
means certain. This point cannot be determined until the characters of the 
feet are known. ; 
The facies of this fauna differs in several points from that of the 
Wasatch. Coryphodon has not yet been discovered in it, and the flesh- 
eaters are very primitive. The suilloid genera are characteristic. 
‘ 
* April, August and October, 1881. 
PRINTED SEPTEMBER 30, 1881. 
