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Show 68 Loup Fork epoch filled the valley of the Rio Grande from its upper waters to an unknown distance toward Mexico. These red and variegated beds cover the stratigraphical axis of the Sierra Madre at this point, although not the water- sbed between the waters of the Rio Grande and Rio Colorado. The geology west of this point will be considered in the chapter devoted to the Sierra Madre and the area west of it. CHAPTER III. THE VERTEBRATE PALEONTOLOGY OF THE SANTA FE MARLS. The earliest information which we possess respecting the existence of vertebrate remains in the lacustrine deposits of the Rio Grande Valley is due to the interest displayed by Hon. Wm. F. M. Amy, then governor of New Mexico. He obtained from the region northwest of Santa F6 the fragments of a lower jaw of a Mastodon product as, Cope, and sent them to the Smithsonian Institution. This specimen formed the subject of a description by Dr. beidy, who referred the species to his Mastodon obscurns.* The next observations of vertebrate fossils were made by the members of your expedition of 1873. Francis Klett obtained a number of specimens from near San Ildefonso. Following the directions of this gentleman, I made the examination during the season of 1874 which resulted in the discovery of twenty- nine species of Vertebrate, of which all but four are determinable. Some of these have been already described in my report to you, published in the Annual Report of the Chief of Engineers for 1874, page 603. The following list embraces the names of all the species and descriptions of such as have been heretofore unknown : CARXIVORA. Canis vr sinus, Cope, Proceedings of the Philadelphia Academy, 1875, p. -. This large dog is the largest carnivorous animal observed in the fauna, equaling in dimensions the Ursus americanus. It approaches the Amphicyo^ s in the great development of its tubercular molar teeth, and is allied to the A. Haydenii, Leidy, from the Loup Fork beds of Nebraska. It is distinguished for the large size of the canine teeth and the small size of its premolar teeth. The premolars are separated from each other and from the canine by short subequal diastemata; but the fourth premolar and the true molars form an uninterrupted series. The first tubercular molar is larger than the last premolar, and the second tubercular is but little smaller than the same tooth, and has its single flat root so grooved as to foreshadow the two- rooted condition seen in the A. Haydenii. The mandibular ramus is deepened posteriorly, and is remarkable in the great anterior prolongation of the masseteric fossa, whicb reaches as far as below the middle of the sectorial molar tooth. The dimensions are as follows: Length of molar series from alveolus of canine, 0m. 121; length from same to sectorial molar, 0m. 061; length of sectorial, 0m. 031; width of crown of sectorial, 0m. 012; depth of ramus at posterior border of sectorial, 0m. 055; depth of ramus at anterior border of sectorial, 0m. 049; depth of ramus at first or simple premolar, m. 038; long diameter of canine tooth, 0m. 023. From A. haydenii the species differs in the position of the tubercular molars, being on the continuous alveolar border, as in typical dogs, in the one- rooted second tubercular tooth, aud in the anterior extension of the masseteric fossa. Canis sasvus, Leidy, Extinct Mamni. Dakota and Nebraska, p. 28. A mandibular ramii of this species, which is, as Leidy observes, much like the Canis lupus. Canis vafer, Leidy, loc. cit., p. 29. Mustela nambiana, Cope.- Maries nambiamis, Cope, Report on Vertebrate Fossils of New Mexico, Annual Report Chief of Engineers, 1874, p. 603. ARTIODACTVLA. Dicroeerus gemmifer, Cope. Merycodus gemmtfer, Cope, Annual Report of United States Geologcal Survey Territories, 1873, p. 531. The genus Dicroeerus was proposed by Edouard Lartet in 1839 for ruminants which combine the character of the deer and the antelopes. In 1851 the genus was further defined by him, and it was observed that in some of the specimens the horns are continuous with the frontal bones, as in the antelopes, & c, while in others there is a union * Report of the Geological Survey of the Territories, vol. i, ( 4to,) p. 235. |