18S1.] 



27 



[Cope. 



Cosoryx Leidy, and Blastomeryx Cope. I had already* suggested that 

 the former genus Is the ancestor of the Cervidse, but subsequently! re- 

 marked : "It is not probable this genus is the immediate ancestor of Cervus. 

 from the fact that the molar teeth display in their prismatic form a higher 

 degree of specialization than belongs to that genus. It is probable that 

 the true ancestor combined the dental type of Cervus with the distinct 

 roots and short crowns of the molars, with the type of horns here de- 

 scribed." I at that time included a species {Cosoryx gemmifer Cope) in the 

 genus, provisionally, which has the type of molars in question. Having 

 discovered another, larger species, which has the same type of molars, I 

 at once distinguished the provisional group in which I had placed the 

 G. gmnmifer, Blastomeryx, as a genus ; and in describing the species (J?. 

 iorealis) observed as follows : 



"In brief, its molars differ from those of Cosoryx ("Dicrocerus") much 

 as those of the deer differ from the molars of the antelope. While Cosoryx 

 ("Dicrocerus") was probably the ancestor of Antilocapra, Blastomeryx 

 was the ancestor of Cervus or Cariacus." This opinion expresses all the 

 information I possess on the subject at present. It remains to ascertain 

 the structure of the anterior feet in Hypisodus, which is the earliest genus 

 of Ruminantia known to have prismatic molars. 



The following table will represent the views expressed in the preceding 

 pages : 



1 Bovidae. 



Tragulidse. 



Camelidge. 



Hyopotamidge. Oreodontidae. Poebrotheriidae. 



Quadritubercular Buno- 

 'donta. 



Tritubercular Bunodonta. 

 (Pantolestidte.) 



* Proceedings Academy Philadelphia, 1874, p. 149. 



t Report Expl. Surv. W. of 100th Mer. U. S., G. M. Wheeler ia charge, iv, pt. ii, 

 p. 349, 1877. 



