8ti BULLETIN OF THE 



proximal end obviously diseased, so that it does not merit description ; the oidy 

 fact of importance which it shows is the comparative slenderness of the bone. 



So far as the material will enable us to judge, the feet of Cosoryx differ in no 

 important respect from those of Blastomeryx, and the same statement applies to 

 the long bones of the limbs. 



Restoration of Cosoryx furcatus. 

 (See Plate I.) 



This drawing is made from the specimen already described, completed by 

 fragments of others, while the feet are drawn from Blastomeryx; the cervical 

 vertebrae are represented only by the axis, the others being conjectural, as are 

 also the anterior dorsals. The skull is taken chiefly from that of the closely 

 allied European genus, Pa!ceomeryx, and from specimens of the large Cosoryx 

 teres, Cope, belonging to the Smithsonian Institution. The fortunate associa- 

 tion of the mandible in the same specimen with the vertebrae, pelvis, scapula, 

 etc., gives a very useful standard as to the length and character of the skull, 

 position of the molars, etc. It may be assumed with some confidence that the 

 drawing gives a fairly accurate representation of the animal. Marsh's account 

 of the feet of Cosoryx shows that they were constructed much like those of Blas- 

 tomeryx. In general appearance Cosoryx seems to have had the same light, 

 graceful build as Antilocapra , but with a very different skull and deer-like 

 antlers. The proportions of the limbs also differ somewhat, the hinder cannon- 

 hone being considerably longer than the fore, while in the prong-buck they are 

 of nearly the same length. Cosoryx was a much smaller animal, the bones are 

 all more slender than in Antilocapra, and the carpal and tarsal bones are much 

 higher and narrower proportionately. 



The view held by Cope that Cosoryx is the ancestor of Antilocapra is very 

 probably the true one. So far as the dentition, the vertebrae, and the limbs are 

 concerned, the differences between the two genera are only such as might be 

 expected to occur between a Miocene and a recent ruminant. A distinction of 

 some importance, however, consists in the character of the horns. In Cosoryx 

 they are branched, but probably not deciduous antlers; in Antilocapra, a core 

 with a horny sheath, which, however, differs strikingly from the horn of the 

 typical Cavicornia. But the unique branched horn of Antilocapra not improb- 

 ably indicates, as has been suggested by Cope, a remnant of a former branching 

 of the bony core itself, and so this difference does not preclude a genetic con- 

 nection between the two forms. In Cosoryx the antler was almost certainly 

 covered with skin; its smooth surface, as Schlosser points out, shows that it 

 could not have been naked, as in the true deer. 



Both Blastomeryx and Cosoryx are probably to be derived from the species re- 

 ferred to the former genus which occur in the John Day beds, but there is no 

 form yet known in the White River which could have given rise to these John 

 Day ruminants. The latter are most probably descended from some Palaio- 

 meryx of the Old World, which migrated to this continent. The very close con- 



