316 STKOPSIS OF THE VEKTEBRATE FAUTSTA OF THE PUERCO SERIES. 



Measurements of Posterior Limb. At. 



( anteroposterior 025 



Diameters distal end of tibia -^ 



i transverse OdU 



Lengtli of plialange 024 



anteroposterior 013 



Diiuneters of distal end -J 



transverse .011 



Depth of ungnis 



f at tendinous insertion 019 



I anterior to tendinous insertion 013 



I at phalangeal surface 009 



Width of unguis [ at tendinous tuberosity 006 



[ anterior to tendinous tuberosity 005 



CONORYCTES Cope. 



Proe. Amer. Pliil. Soc, 1881, p. 486; Tertiary Vertebrata, 1885, p. 198. Hexodon Cope; Amer. Naturalist, 1884, 

 p. 794. 



Additional material representing the type species of this genus enables me to 

 give the chai'acters more fully than hitherto. The C comma experienced an early 

 obliteration of the details of the structure of the crowns of the molar teeth through 

 the thinness of the enamel layer and the mastication of hard substances, so that they 

 are seen in but few specimens. 



The superior true molars, and the first premolar, have two external conical cusps, 

 and an internal triangular table, whose inner angle is produced downwards to a line 

 with the apices of the internal cusps. The inferior premolars and the first premolar 

 have the anterior part much elevated above the posterior. The former consists of a 

 large external and a small internal cusp joined to near their summits, except on the 

 first premolar which has but one anterior cusp, which is simple acute cone. A rudi- 

 mental lifth cus]) is present on the true molars. 



The ma.stication in this genus is aftected by a scooping action of the keels of the 

 inferior molars against the internal table of the superior molars by a motion which is 

 partly transverse, as in Onychodectes. 



There are probably four infei'ior i)remolars in this genus, but the anterior two 

 have but one root each, and are close together. My supposition that some specimens 

 had but three premolars led me to propose the genus Hexodon, which is now aban- 

 doned. 



The position of the genus is doubtful, owing to the absence of the ungual pha- 

 langes. It is probabl}' Ci'eodout rather than Condylarthrous, for two reasons; one is 

 the close resemblance of the dentition to those of Onychodectes and Hemiganus, 

 between which it takes a natural position. The other is, that it displays no resem- 

 blance to any of the Condylarthra in the details of its structure. 



But one species is known to me. 



