428 0. 0. Marsh — Gharoccters of the genus Coryphodon. 



torj lobes of this genus are somewhat similar to those of Dino- 

 ceras. The cerebellum was proportionally large, and widely ex- 

 panded transversely. Its peculiar form is shown in figure 1, 

 which is drawn from a cast of the brain-cavity of C. hamatus. 



portion of the brain nearly or quite equaled the hemis- 

 pneres in size, thus differing widely from any known mammal. 

 T^ere is a well marked pituitary fossa, but no clinoid process. 



The foramina for the exit of the optic nerves are small, but for 

 the others very large. The brain as a whole was very low in 

 grade, and precisely such as might be expected in a mammal 

 from the oldest tertiary deposits. 



The skeleton of Coryphodon {Bathmodon) presents many fea- 

 tures of interest, but only a few can now be mentioned. The 

 limbs were comparativly short, and the femur has a third 

 trochanter. The feet are especially interesting, as they present 

 a primitive or generalized type. The manus and pes had each 

 five short digits.* 



The various characters shown in the skull and limbs of Cory- 

 phodon indicate that the animals of this genus were essentially 

 five-toed Perissodactyles. They evidently represent a distinct 

 family which may be called Coryphodontidce. Their geological 

 horizon in this country is near the base of the Eocene, in the 

 deposits named by the Survey of the Fortieth Parallel, under 

 Clarence King, the Vermillion Creek series. The remains 

 of the family at present known in this country are from Utah, 

 Wyoming, and New Mexico. 



Yale College, New Haven, April 15th, 1876. 



* Prof. Cope lias recently published (Catalogue of Eocene Vertebrata from New 



Mexico, p. 28, 1875), a figure of the " Hind foot of Ba ' ' " " ^ " " ' '"'* 



in several respects, the hallux, for example, having tl 



