1877.] ^3 [Cope. 



tainly distinct from Dierocerus Lartet. The discovery of a second species 

 of the group, which displays the characters there pointed out, in a still 

 more striking degree than the species on which it was formed, renders it 

 necessary to introduce the genus formally to the system. In brief its 

 molars differ from those of Dierocerus much as those of the deer differ from 

 the molars of the antelope. While Dierocerus was probably the ancestor 

 of Antilocapra, Blastomeryx was the ancestor of Cervus or Gariacus. 



The superior dental formula is I. ; C. ; Pm. 3 ; M. 3. The molars 

 all have two pairs of crescents excepting the last premolar, where the pos- 

 terior pair are rudimental. The external face of the anterior crescent in 

 all the molars presents a groove, which is bounded posteriorly by a vertical 

 ridge. The posterior crescent is directed a little inward posteriorly on -the 

 true molars. The palate is much contracted in front of the first molars. 

 The horns stand above the posterior parts of the orbits ; their section is 

 triangular, the posterior angle being rounded, and the external produced 

 and acute, bounding the orbit outwards and backwards. There is no trace 

 of burr. The temporal fossae approach so as to be separated only by a 

 rather wide and low occipital crest. 



Measurements. M. 



Total length of skull 320 



Length of molar series - 107 



' ' premolar " 049 



' ' second premolar 016 



Width " " Oil 



Length of first true molar 020 



Width " " ... x 015 



Width between bases of horn-cores 050 



Transverse diameter of horn- core two inches from base. . ,040 



Width between external borders of first true molars 078 



Width of palate in front of first premolars 028 



This species was as large as the black-tailed deer, Gariacus macrotis. It 

 was found by my assistant, J. C. Isaac, in the Upper Miocene of Montana. 



Cervus fortis sp. nov. 



This deer is of large size, much exceeding any living species of the 

 family Gervidce. It is represented in my collections by a superior molar 

 of the left side, and very probably by other remains which accompanied it, 

 viz. : a mandibular symphysis with incisor and canine teeth ; calcaneum. 

 astragalus, vertebrae, etc. These were found at the same time and place 

 by George M- Sternberg-, M.D., U. S. A., already well-known by his in- 

 teresting discoveries in the cretaceous formation of Kansas. 



The plicae which mark the anterior extremities of the external crescents 

 are very prominent, and are directed forwards rather than outwards. The 

 median lakes are narrow and well separated medially. The posterior lake 

 has a strong fold of its internal border, forming a lobe directed backwards. 



