26 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 91 



The upper molars (type, fig. 14, «), M^ and M^, in No. 15789 

 resemble closely those in Protoselene opisthacus, but the difference 

 in size between these teeth is more noticeable than in the Torrejon 

 form, with M^ distinctly larger than in P. opisthacus. The external 

 cingulum is more prominent and more markedly crescentic about 

 both the paracone and metacone. The mesostyle is well developed 

 as in certain specimens of P. opisthacus but more conical and dis- 

 tinctly separated from the crest which extends between the paracone 

 and metacone. In P. opisthacus the mesostyle extends outward as 

 a spur or projection from this crest. 



Additional material obtained in 1939 includes several more isolated 

 teeth, but in particular two maxillary portions: No. 16203 with M^ 

 and M' and No. 16182 with M- and M^ (fig. 14, l). The newly ac- 

 quired upper teeth show Dracoclaenus griphus to run somewhat larger 

 than P. opisthacus. The two forms are most nearly alike in M^, but 

 the posterior upper molars show less resemblance. To the greater 

 size of M^ is further added a much better development of the parastjde 

 than in P. opisthacus. M^, not hitherto known, is seen to be more 

 like M^ than in P. opisthacus. This tooth is relatively larger than in 

 the Torrejon form and, although approaching a triangular outline, 

 shows a more distinct hypocone and much better developed proto- 

 conule and metaconule. 



A somewhat distinctive upper dentition from the Wagon Koad 

 Ridge locality, including P^-M^, No. 15703, resembles the type in most 

 characters of the molars but has a weaker hypocone on both molars 

 and a very weak metaconule on M^. The anteroexternal angle of M- 

 extends forward even somewhat more, suggestive of the oxyclaenids, 

 but has the mesostyle, particularly in M\ as in No. 15789. The 

 external cingulum is not so crescentic around the outer cusps, the 

 outer wall being more nearly straight. P* is similar but a little 

 smaller than in Nos. 15705 and 15780. This specimen. No. 15703, may 

 represent a distinct species of Dracoclaenus or may possibly be an 

 oxyclaenid, close in size to Oxyclaenus simplex; however, P* and M^ 

 more closely resemble the Dracoclaenus material. 



The lower jaw portion. No. 15773 (fig. 14, c), considered by com- 

 parison to represent Dracoclaenus griphus., also resembles material 

 of Protoselene. It corresponds closely in size to P. opisthacus but has 

 the paraconid on Mi and Mg more internal in position, and in 

 M2 it is not placed so low and is less reduced than in P. opisthacus. 

 The talonid basin is apparently not so deep and is narrower between 

 the hypoconid and entoconid. A slight accessory cusp is present on 

 the anterior crest of the entoconid nearly as prominent as in P. 

 opisthacus. 



