512 University of California Publications in Geology [Vol. 11 



CAMELIDAE 



Remains of camels are among the most common fossils found in 

 the Barstow beds. Unfortunately the teeth do not resist destructive 

 processes as well as those of the horses, and in absence of complete 

 skeletal material little but scattered foot bones remain for study. 

 Almost the only basis for comparative study of the camels seems to 

 be furnished by the astragali. Of these there are 

 at least four types, graded according to form and 

 size. One is a small form (compare fig. 98), of 

 which the astragalus is a little more than 40 mm. 

 in greatest diameter; others are much larger (com- 

 pare figs. 100 and 101) ranging to a length between 

 80 and 90 mm. It is possible that the smallest of 

 these is merely a diminutive type of the next in 

 size, but a considerable number of specimens seem 

 not to show an intergradation. The largest of the 

 Barstow forms are much smaller than the largest 

 forms in the Rieardo fauna. At least two of the 

 Barstow types (compare figs. 98 and 99) evidently 

 represent the genus Procamelus, as nearly as can 

 be judged by the dentition and the metapodials 

 referred to this group. The largest forms of the Barstow fauna pre- 

 sumably represent the genera Alticamelus and PUauchenia (compare 

 figs. 100 and 101). The broader specimens of the larger group are 

 presumably PUauchenia, the narrower ones Alticamelus. 



A small astragalus with a portion of the dentition, no. 21554 

 (figs. 96 and 98), representing the smallest form known from the 

 Barstow seems to represent Procamelus. The astragalus is small and 

 narrow. The dentition represents the last two milk molars. The form 

 is evidently a young individual of one of the two species smaller than 

 Alticamelus and presumably to be referred to Procamelus. 



The largest specimen representing the limbs is no. 21552, fig. 92, 

 and is a very large and slender anterior metapodial about 70 per cent 

 longer than the anterior metapodial of a Recent camel. This speci- 

 men presumably represents a form of Alticamelus. The largest speci- 

 men representing the dentition in the Barstow fauna is a mandible 

 (fig. 104), no. 21553, with two posterior molars, the roots of the pre- 

 molars, and the canine. On this specimen all of the four premolars 

 have been present. This mandible may belong also to Alticamelus. 



Fig. 89. Mery- 

 oochoerus? buwaldi, 

 n. sp.? Astragalus, 

 no. 21486, natural 

 size. Barstow Mio- 

 cene, Mohave Des- 

 ert, California. 



