126 Bulletin American Museum of Nahiral History. [Vol. X, 



p. robust us. P. occidentalis. P. g^raciiis. 



MM. IMM. MM. 



Length of last three pms. and ms 152 126 iii 



T33 

 126 



135 

 Length of last three pms. and / 106 go 77 



first two ms ( 85 76 



88 76 



92 



Two incomplete metapodials in the collection, which are of 

 suitable size for those of this species, show lack of bony union, 

 notwithstanding the fact that the epiphyses are completely joined 

 to the shaft. It is not certain, but there is evidence, that these 

 metapodials belong to the fore foot, in which event it will not be 

 surprising to find in more complete and perfect specimens that 

 these bones are not coossified in this species, except in old indi- 

 viduals. In the hind foot the metapodials are completely united, 

 as is shown by several specimens. In one specimen, which corre- 

 sponds in size with P. occidentalis, the proximal part of the 

 cannon bone shows lack of bony union for a distance of nearly 

 two inches down the shaft. 



Pliauchenia Cope. 



The only character so far known in which this genus differs 

 from Froca?>ielus is found in the absence of the second lower 

 premolar, and as this constitutes an important step in the dental 

 evolution of the Camels, the species displaying it are entitled to 

 rank as a separate and distinct genus. The exact stratigraphic 

 position of the group is not known, owing to the imperfect collect- 

 ing that has been done in the Loup P'ork Beds. It is generally 

 stated that Pliaiiclienia was contemporaneous with Procamelus in 

 the Loup Fork, and comes from the same horizon, but of this one 

 cannot be certain. It must be remembered that this deposit is 

 several hundred feet in thickness in places, and it would not be a 

 matter for surprise if it is found, upon more careful investigation, 

 that Procamelus comes from the lower levels and Fliauc/ie/iia 

 from the up])er strata of the same bed. 



Three species have been described by Cope, of which two are 

 from the Loup Fork of New Mexico and one from the later 



