R. S. Lull — New Tertiary Artie-dactyls. 127 



tended cranial region, and this shows in the brain as 

 well, for. not only is the entire organ relatively longer in 

 Blast ornery 'x, but the same proportions are borne out in 

 the individual lobes and convolutions, which are otherwise 

 quite comparable in the two forms, differing- only in very 

 minor details. The teeth also are very similar, differing 

 mainly in the relatively larger posterior molar in 

 Blastomeryx. They are comparable in length of crown, 

 in the presence of the style between the two inner 

 crescents of the molars, and in the rugosity of the 

 enamel. They also compare in the character of the 

 parietal crest, and in the position of the horns above the 

 posterior limitation of the orbit. This Blastomeryx 

 differs from Dromomeryx as defined by Douglass in 

 its much smaller size, the character and much smaller 

 size of the horns, the presence of the superior canine, 

 and the fact that the cheek teeth show no tendency toward 

 hypsodonty. The posterior lower molar in the Blasto- 

 meryx shows a style ("median outer pillar") as in 

 Dromomeryx. The others are too much worn to show 

 either this character or the presence of the " Palceomeryx 

 fold" if such existed. 



Summary. 



The genus Blastomeryx was proposed by Cope in 

 1877 11 to include the species formerly described by him as 

 Dicrocerus gemmifer from the middle Miocene and 

 which he differentiated from Dicrocerus by the fact that 

 in the latter the "true molars [were] without or with one 

 rudimental accessory basal column," whereas in Blasto- 

 meryx the "true molars [were] with more or less devel- 

 oped basal columns." Matthew in 1908 12 gives a clear 

 description of the generic characters of Blastomeryx and 

 summarizes the known species, giving the list as follows : 



Lower Miocene : B. advena Matthew, B. primus 

 Matthew, and B. oleotti Matthew. Of B. gemmifer he 

 says: 



' ' The type specimen of B. gemmifer is a third lower molar and 

 is a little larger and more robust [than in B. advena], agreeing 

 more nearly with B. primus and oleotti, and not clearly separable 

 from them; but probably if it were better known its stage of 



11 Cope, E. D., U. S. Geog. Surv. West 100th Merid., vol. 4, Paleontology, 

 p. 350. 



12 Matthew, W. D., Bull. Amer. Mus. Nat. Hist., vol. 27, pp. 535-562. 



