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Show 70 I This species is dedicated to Brigadier- General A. A. Humphrey*, Chief of Engineers, U. S. Army, in recognition of the enlightened interest in all departments of scientific investigation exhibited in his long and able administration. PJiauchenia vulcanwum, Cope, sp. no v. Represented by the left maxillary bone of a camel of about the size of the existing dromedary, and considerably larger than the species last described. The dental formula is molars 4- 3. The first premolar is only removed from the 6econd by a diastema equal to the long diameter of the latter. The latter has no inner cingulun), while in the third it is so strong as to constitute an internal crescent. The third is much larger, and exhibits the usual single external and single internal crescents. The first molar is stout, long- rooted, and furnished with a strong ridge on the outer side, bounding the posterior crescent- bearing column in front. There is a weak ridge on the middle of the anterior column, and only a rudiment on the last premolar. There are no cingula on either the inner or outer bases of the crown. The enamel is nearly smooth. A palato- maxillary foramen issues opposite the anterior border of the base of the third premolar. Measurements. M. Length from posterior border of first premolar to posterior border of first molar. .090 Length of first true molar 030 Width of base of crown of first true molar 024 Length of fourth premolar 019 Width of base of crown of fourth premolar 018 Width of palate- at first true molar 040 The typical specimen was found near Pajuaque, a village of the Pueblo Indians. Various bones of camels of the size of the P. vulcanorum were also fouud, some of which doubtless belong to it. Procamelus gracilis, Leidy, Extiuct Mammalia. Dakota and Nebraska, p. 155. Specimens which present the measurements of this little known species are provisionally referred to it. Procamelus occidental**, Leidy, loc. cit., p. -. The cranium of this species is not unlike that of the llama, but is, as might be anticipated from the dental characters, more elongate. I am also able to demonstrate on this species, as I already have on the P. heterodontus,* Cope, the presence of the second incisor teeth. As the specimen described is not quite adult, the first pair do not appear, but the alveolar border is excavated at their normal position. An extensive fossa is situated above the posterior premolar series of teeth, and greatly contracts the middle of the facial part of the skull. The anterior part of the maxillary bone is concave, and overhung by the superjacent regions, causing a second fossa, which contracts the palatal face. These foss ® are represented by rudiments in the Auchenia lama. In addition, the cavities known as " larmiers" in the Cervidas are well developed in this species, being many times as large as in the llama, and quite equal to those possessed by some deer. The supraorbital foramen communicates with the superciliary border by an open fissure; the lachrymal bone is large. The cranium resembles that of the llama in its moderate sagittal crest, elongate paramastoid process and otic bula, and the downward production of the pterygoid bones. The incisive foramina are narrow and distinct. The ulna and radius are thoroughly co- ossified. The carpus displays the characters of the Camelidas in the absence ot trapezium and distinctness of trapezoides, aud the suhequality of the magnum and unciform facets of the lunce. There are but two metacarpals, which, in the specimen described, are only co- ossified in their proximal half. As the last molar tooth is only two- thirds protruded, the present animal is not fully adult; in an older specimen, the cannon- bone is doubtless completed. In general proportions, the Procamelus occidentals much resembled the llama. Merychyus medius, Leidy, Extinct Mammalia of Dakota and Nebraska, p. 119. One side of the facial region with superior dentition, with other remains, represents this Oreodont. PBRISSODACTYLA. Hippotherium calamarium, Cope, sp. nov. This three- toed horse is indicated by the oval and palatine parts of the skull with the superior dental series of both sides, together with one mandibular ramus, with all its teeth, of an individual from near San Ildefonso, and also probably by molar teeth of two individuals from the Loup Fork beds of Colorado. The species is allied to the * Annual Report of the United States Geological Survey of the Territories, 1973, p. 530. |