486 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 92 
P* of the modern material. In the preserved portion of the fossil P* 
the conical metaconule is even more closely joined to the metacone, 
also in P*, the crest at the anterior margin of the tooth appears better 
developed than in Recent Otospermophilus, almost as prominent as 
in M' but for a much less portion of the width of the tooth. M* has 
a relatively smaller talon portion, and shows a small conical cusp 
in the basin somewhat lingual to the center. Moreover, none of the 
upper teeth of the type show a mesostyle as seen in upper teeth of 
some individuals of O. beecheyi. 
The lower teeth in jaws referred to C. bensoni even more closely 
resemble those in Otospermophilus forms. The differences are not 
striking and consist principally of a slight but distinct notch dividing 
the crest between the metaconid and protoconid of M, (suggestive of 
P,), a somewhat more deepened basin immediately adjacent to the 
crest between the protoconid and hypoconid in all, and a relatively 
small talonid on M3. 
PRODIPODOMYS 7? MINOR (Gidley) 
A single right mandibular ramus, No. 10499, in the Benson collec- 
tion apparently represents an ancestral form close to Dipodomys. The 
specimen includes the incisor and P,, and exhibits the alveoli for the 
molars. It is incomplete anteriorly along the inner wall of the 
incisor and the angle is not entirely preserved. 
The jaw of Prodipodomys ? minor is a little smaller and slenderer 
than in Dipodomys ordii. The symphysial portion and ascending 
ramus are shorter and the coronoid relatively smaller than in D. ordii, 
although the length of the tooth row is comparable, as indicated by 
the alveoli. The masseteric crest is for the most part indistinct but 
terminates anteriorly in a conspicuous swelling, not so prominent, 
however, as in most recent material. Also, the fossa lingual to the 
ascending ramus and posteroexternal to the molars is not nearly so 
deep or so well defined. 
P, conforms very closely to that in D. ordii, and the pattern can 
be closely if not exactly matched in Recent teeth. M,, however, was 
distinctly larger than in PD. ordii, and appears from the configura- 
tion of bone in the bottom of the alveolus to have had small roots, 
as indicated for Prodipodomys kansensis. M, was a little smaller 
than M,, and M; appears to have been distinctly small, smaller than 
in D. ordit. 
A. E. Wood (1935, pp. 155-156) referred a specimen, Amer. Mus. No. 
27790, from the Curtis ranch locality to this species. It seems prob- 
able, however, that the form represented is not the same. Wood 
states that the molar (M,) is rootless, an advance over the rooted 
§C. W. Hibbard, Trans. Kansas Acad. Sci., vol. 42, p. 458, 1939. 
