THE MAMMALIA OF THE DEEP RIVER BEDS. 167 



Fam. Indet. 



HYPERTRA.GULUS CALCARATITS Cope. 



Bull. U. S. Geol. and Qeogr. Sure., No. 1, 1874, p. 26. 



A mandible, which is indistinguishable from that of the species named, was 

 found in the lower beds of the Deep River valley, and some specimens from the 

 upper, or Loup Fork, beds of the same locality seem to indicate that the same or a 

 closely allied genus was continued up into the latter series, but the specimens are too 

 fragmentary for certain reference. 



BLASTOMEEYX Cope. 



U. S. Qeogr. Sun. W. of lOOlli Mer., Vol. IV, PI. II, p. 350. 



The status of this genus is very 'obscure and uncertain. The name was origi- 

 nally applied to ^TS of a small animal from the upper Loup Fork of Colorado and 

 ISTew Mexico, which appears to be very much like Cosoryx, differing from the latter 

 in the shortness of the molar crowns and better development of the basal pillar. So 

 very little is known of the dentition of this animal that its relationships are quite 

 indeterminate beyond the obvious fact of its alliance with Cosoryx. The much 

 larger and more robust species from the lower Loup Fork or Deep River, which has 

 been referred to this genus, not improbably represents a very different one, but 

 materials are lacking for an exact comparison. This Deep River species is in many 

 ways similar to the larger species of Palceomeryx from the upper Miocene of Europe, 

 and perhaps should be referred to that genus, though in the present state of knowl- 

 edge it would be premature to do so. This doubt is justified by the fact that the 

 mandibular dentition of B. oorealis is still unknown, and we cannot therefore deter- 

 mine whether the lower molars possessed the very characteristic " Palseomeryx fold," 

 and it is uncertain whether the type of the European species had developed horns. 

 Schlosser does not regard the presence or absence of horns as a character of generic 

 value, but with this view I am unable to agree. Further, the character of the horns 

 and the shape of the occiput are different from anything which has been observed in 

 the European types. For these reasons, the name Blastomeryx may be provisionally 

 retained. However, by whatever name we call it, there can be little doubt this genus 

 represents a more or less modified migrant from the Old World, not only because of 

 its close similarity, or even identity, with some of the genera of that region, but also 

 because it represents a new element in the American fauna, no form being known 

 from the White River or John Day formations from which it could be derived. That 

 an interchange of mammals between the two continents took place at some time 



A. p. s. — VOL. XVIII. v. 



