Cope.] 6±£ [Dec. 7, 



to near their free summits. There are the usual low marginal tubercles on 

 the heels. That of the fourth premolar is a short simple edge. 



Measurements. M. 



Length of four molars on basis 028 



" " three true molars 0212 



" " second true molar 008 



Elevation of cusps of molars 0045 



Length of last true molar 0067 



Width of last true molar 0030 



Elevation of last true molar in front 0035 



Found by D. Baldwin. 



MlOCL^ENUS CUSPIDATUS, Sp. nOV. 



The species of this genus known to me are, with the present one, nine 

 in number'. They range in size from that of a rat (M. minimus) to that ot 

 a wolf (M. ferox). The general osteological characters of the last named 

 species are best known, and are described in the Proceedings of the Amer- 

 ican Philosophical Society, 1883, p. 547. In two of the species the supe- 

 rior dental series only is more or less known, and one species rests on 

 mandibular dentition only. In the remaining seven species the dentition 

 of both jaws is more or less known. The species may be arranged in 

 groups as follows : 



I. The posterior heel of the second inferior molar bordered by a curved 

 edge or crest. 



a. Posterior cingulum of superior true molars obsolete ; M. minimus, 

 aa. Posterior superior cingulum weak ; M. turgidus. 

 aaa. Posterior superior cingulum large, angulate ; M. corrugatus ; M. 

 ferox. 



II. The posterior heel of the second inferior molar supporting a cusp. 



a. Posterior inner cusp of superior molars small, present on m. ii only ; 

 31. cuspidatus. 



aa. Posterior inner cusp large, present on m. i and m. ii ; premolars 

 small, M- subtrigonus j premolars large, M. opisthacus (Semithlceus milii 

 olim). 



III. Second lower molar unknown. 31. protogonioides, and 31. mandib- 

 ularis. 



The supposed 31. baldwini, resembles closely the species of Hemithlceus. 



It is probable that two genera are here included under the head of 3iio- 

 clcenus. If the character is permanent, these will be distinguished as fol- 

 lows : 



Third superior premolar with internal tubercle 3Iioclcenus. 



Third superior premolar without internal tubercle Oxyclomus. 



The species of Mioclamvs are 3f. turgidus (type) ; and very probably 

 M. opisthacus, minimus and 3f. subtrigonus ; but the diagnostic tooth has 

 not been seen in them as yet. The species of Oxyclcenus are : 0. cuspidatus 



