NATURAL SCIENCES OF PHILADELPHIA. 259 



This species is dedicated to General A. A. Humphreys, Chief of 

 the Topographical Engineers, in recognition of the enlightened 

 interest in all departments of scientific investigation, exhibited in 

 his long and able administration. 



Pliauchenia tulcanorum, Cope, sp. nov. 



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 second by a diastema 

 equal to the long diameter of the latter. The latter has no inner 

 cingulum, 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 poste- 

 rior border of first molar 090 



Length of first true molar 030 



Width of basis of crown of first true molar . . . .024 



Length of fourth premolar 019 



Width of base of crown of fourth premolar . . . .018 

 " " palate at first true molar 040 



The typical specimen was found near Pojuaque, a village of the 

 Pueblo Indians. Various bones of camels of the size of the P. 

 vulcanorum were also found, some of which doubtless belong to it. 



HlPPOTHERITJM CALAMAFvITJM, Cope, sp. nOV. 



This three-toed horse is indicated by the oral 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 indi- 

 vidual 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 H. paniense, Cope, and differs from 

 the H. occidentale, H. speciosum, and H. gratum of Leidy, in the 

 relative form and size of the interior dentinal column. In the two 

 species first named, this column is subcylindric and equal to or 

 smaller than the posterior internal columnar fold; in the three 

 species last named the anterior column is flattened or oval in 

 section, and often larger than the posterior columnar fold, and 

 submedian in position. 



In the typical or New Mexican specimen the interior column is 



