202 Bulletin American Museum of Natural History. [Vol. X, 



This is an indeterminate type. It is distinguished by angula- 

 tion of ectoloph in ra- (as in C. elepkanfopus, cotype) ; perhaps 

 also by the more transverse direction of hypolophid in nig ; 

 second incisors only slightly larger than first and third (as in C. 

 elepluintopus, cotype). The nearest resemblance is therefore 

 to C. elep/iaiitopus, from which it is distinguished by larger size. 

 Superior molars No. 4366, from New Mexico, furnish a transition 

 in the angular form of the ectoloph of m- to the C. testis type. 

 Altogether C. repandus is of very doubtful validity. 



19. C. cinctus Cope. 



C. {Ectacodon) ductus. Type: No. 4341, Am. M us., Cope Coll. Superior 

 molars complete. A strong cusp appearing at postero-external angle of m-. 

 Loc, Big Horn, Wyoming. 



The distinctive feature of this type, viz., the quadrate form and 

 postero-external basal cusp of m^^ (Fig- 15), and to a less extent on 

 m-, are either individual variations or valid specific characters. 

 They are certainly not generic. 



Lower teeth which may possibly be correlated (Nos. 4329, 4334, 

 266) have a triangular heel upon the last lower molar (Fig. 16), 

 with entoconid very distinct and extremely short and oblique 

 hyi)olophid. 



24. C. testis Cope. 



24. C. {Mctalophodon) testis Cope. Type : No. 4317, Am. jMus., Cope Coll. 

 Superior molar series. Originally distinguished by reduction of posterior cres- 

 cent spur in m-. 



Definition. — -Sup. molars=i69 2 to 1825. Inf. molars=i72 ? to 192;?. 

 Third superior molar typically oval, with oblique posterior crest with primitive 

 paracone, mesostyle and meta-crescent more or less distinct. Third inferior 

 molar with oblique hypolophid, entoconid 2 reduced or vestigial. Second 

 incisor the largest. 



This includes the most completely known Coryphodon. It has 

 been heretofore described by Earle and the writer as C. radians., 

 but is now found to be distinct. The identification with Cope's 

 type of C. testis is made by means of a careful comparison with 

 the superior molars in the female skull No. 2963. The form and 

 measurements are identical. As this skull undoubtedly belongs 



