220 MEMOIRS OF THE CARNEGIE MUSEUM. 
specimen we have also figured. These teeth which are unmistakeably referable 
to Moropus give us all that is at present known of the dentition of the Chalicotheres 
of the John Day formation (see Fig. 5). 
In general proportion and details of structure P* and * of M. oregonensis do 
not present any important differences from those of M. elatus, except the slightly 
more brachyodont crowns and a less development of the parastyle. The molars 
which are provisionally referred to M. oregonensis are also more brachyodont 
than in M. elatus, and the parastyles less prominent, especially on M! and M? 
(see Fig. 5: 2, 5,6, 7 and 8). M®? appears to be proportionally broader and shorter 
than in M. elatus, but otherwise there is little or no difference in the detailed 
structure of the teeth. 
Whether the teeth which are recognizable as belonging to the animal described 
as oregonensis by Leidy may ultimately be found to belong to one or the other of 
the animals described by Marsh as M. distans and M. senezx, is a question which 
Fia.5. M.oregonensis Leidy. 1-2, P!and M!'of right Fic. 6. The type of M. distans Marsh. 1, 
side (type specimen described by Prof. Leidy; 3-4, P? and duplex bone, a, first phalanx, codssified with 6, 
P! of left side; 5, M* of right side (8, 4, 5 probably be- the second phalanx; 2, cuboid; 3, second pha- 
long with Leidy’s type); 6-7, M! and M7?) (No. 10030a, lanx. X#. Drawn from Marsh’s type. The 
Peabody Museum); 8, M%, external view of No. 7259, A. bone represented by 1 probably belonged to 
M. N. H., and a portion of the malar bone, showing the digit III of the manus. 
inferior border of the orbit. 
the future alone can decide. Marsh’s material from the John Day consisted simply 
of fragmentary bones of the feet, generically, but not specifically, recognizable. 
It may well be that the event will prove the identity of M. oregonensis. (Leidy), 
with either or both of the two so-called species of Marsh. Judging from the 
dentition, M. oregonensis was a smaller animal than M. elatus of Nebraska. 
The bones recently described by Merriam (Bull. Dept. Geol. Univ. Calif., 
Vol. VI, pt. ii, pp. 267-271 (1911)), without giving them a specific name, but for 
which we suggest the name M. merriami, coming from the Virgin Valley Beds, 
