4 Bulletin. American Museum of Natural History. [Vol. XXXIV, 
This is intermediate between protenus and altidens. All the specimens 
from the Lysite horizon in the Big Horn and Wind River basins conform to 
the above characterization. A number of specimens in the older collections 
also agree with it, and most if not all of them appear from the character of 
A 
1 
pe 
—\ 
Sm] 
— 
~ 
= 
Fig. 14. 
Fig. 13. Didymictis protenus lysitensis. Upper teeth of type skeleton, crown view, 
natural size left side, m! reversed from right side. Lysite beds, Big Horn Basin, Wyoming. 
Fig. 14. Didymictis protenus lysitensis, lower jaw, outer view, patural size. From type 
specimen, fragmentary skeleton from Lysite beds of Big Horn Basin, Wyoming. 
Fig. 15. Didymictis protenus lysitensis, caleaneum and astragalus of type specimen, 
natural size, superior and internal views. 
the matrix or the records of locality to be from the Lysite or the upper 
levels of the Gray Bull. The New Mexican Wasatch has not yielded any 
specimens referable to this subspecies, although some are larger than the 
type of D. protenus. 
Nos. 2831, 4230, 15640-3, 83, 4236, ete., are from the Big Horn Basin, 
12812a, 12775 from the Wind River Lysite. 
Didymictis altidens Cope 1880.1 
Type, No. 4792, lower jaw fragments with m; and ms, from the Wind River Basin, 
Wyoming. 
This species is characteristic of the Lost Cabin horizon, from which Mr. 
1 Amer. Nat., Vol. XIV, p. 746. 
