PETERSON : DESCRIPTION OF NEW RODENTS 169 
Inferior dentition. 
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THE VERTEBRA. 
The number of presacrals cannot be ascertained, since the type specimen is con- 
siderably damaged, in this region, by erosion. The cervical region is short, as in S. 
fossor; the dorsals are of approximately the same relative size, as well as the ribs and 
the lumbar vertebree. The sacrum is almost entirely weathered away, so that its 
characters cannot be accurately determined. It was apparently long antero-posteri- 
orly and narrow transversely. There remains only a faint indication of four or five 
proximal caudals, which were short, as in S. fossor. 
The Clavicle is heavy, and is imbedded with the specimen in almost its natural 
position. In shape it is similar to that of S. fossor. 
The Fore- Limb (Fig. 4) — The illustration represents the specimen in position, as 
it was found. The skull, lower jaws, the posterior portion of the dorsals, and the 
lumbars have been removed in order to show the characters of the feet. The left 
fore-foot is in position along the side of the skull. The rest of the limb is lost by 
weathering, as is also the left hind limb. The right fore-limb is nearly complete. 
The inferior portion of the scapula is preserved, and presents characters very like 
those of S. fossor. The humerus has alsu the strong deltoid ridge, that terminates 
in the transverse broad plate, which is seen in S. fossor. The transverse diameter 
of the distal end is much expanded. There is a large entepicondylar foramen. The 
radius and the ulna are relatively heavier than in S. fossor, but the length of the bone 
in comparison with the humerus is nearly the same in the two species. 
Manus.—The fore feet in the type are practically complete. ‘They are of ap- 
proximately the same relative size as in S. fossor. In the carpus of S. barbouri, 
there are ten bones. The scapho-lunar bone is of the same size as that of Cynomys. 
The articulation for the radius is convex on the anterior part, and concave antero- 
posteriorly on the posterior part of the bone. In Cynomys, the whole proximal artic- 
ulation is regularly convex antero-posteriorly. On the radial side of the manus in 
the type (No, 1210), there is a small compressed bone, which I take to be the 
