60 THE MAMMALIA OF THE DEEP RIVER BEDS. 



as Cope originally did, and then subdivide that formation into two horizons. The 

 names which Cope first proposed for these subdivisions, the Ticlioleptus and Proca- 

 melus beds respectively, are inapplicable, for the former name is a synonym of Mery- 

 chyus. a genus which occurs in both horizons, and, as now appears, Procamelus prob- 

 ably does also. 



I cannot agree with Cope in regarding the strata of western Nebraska and Cot- 

 tonwood creek, Oregon, as referable to the same horizon as those of the Deep river 

 valley, in Montana. In the case of the former, the determination rests chiefly upon 

 the presence there of Leptauclienia , which Hayden found associated with Oreodon, 

 Iscliyromys, Hyracodon and other characteristic White River forms (seeLeidy, No. 23, 

 pp. 20, 21). Cope has questioned the correctness of this statement as to Leptau- 

 clienia, but it has been abundantly confirmed, that genus being an undoubted White 

 River form. Hayden's reference of Merycoclmrus and Protomeryx to this same hori- 

 zon is almost certainly erroneous and has not been confirmed by subsequent observ- 

 ers. The reference of the beds developed along Cottonwood creek and the upper 

 John Day river, in Oregon, to the Deep River horizon, is determined by the occur- 

 rence in them of a so-called Ancliitlierium and of a species identified as Blastomeryx 

 borealis. It should be noted, however, that the term Ancliitlierium is used in the 

 sense of Mioliippus, the species from Montana which I have called A. equinum is 

 a very different animal and belongs to the group of A. aurelianense, of Europe, which 

 it equals in size. Mioliippus is found in the typical Loup Fork, as well as in the 

 lower series (see Osborn, No. 28, p. 89, under the title f Ancliitlierium parvulum). No 

 great weight, therefore, can be attached to the occurrence of the genus in the Cot- 

 tonwood Creek beds. The presence of Blastomeryx borealis would, of itself, be 

 insufficient for the correlation of the two localities, but the identification of the 

 species is not at all certain. Besides certain minor differences in the teeth, the limb 

 bones from the Oregon beds indicate the existence there of tv/o species, both of 

 which are much heavier than the Montana forms and more like others from the Loup 

 Fork of Kansas. Cope, himself, was struck by the faunal differences of the two 

 localities. He says: "The only species common to the two lists is the Blastomeryx 

 borealis, a fact which indicates some important differences in the two horizons, either 

 epochal or faunal " (No. 8, p. 369). 



Present evidence appears, therefore, to point to the conclusion that the upper 

 series of strata developed in the valley of Deep river form a well-marked horizon at 

 the base of the Loup Fork, and that they are not exactly paralleled by any deposits 

 as yet known elsewhere ; and, further, that the lower series of the Montana strata 

 should be referred to the summit of the John Day, where they form a less distinctly 



