Vol. 4] Sinclair. — Mammalia from Quaternary Cans. 



159 



length of the calcaneum and the width across the fan-like expan- 

 sion at the posterior extremity of the bone is far less. 



The navicular (PI. 20, figs. 5-6) has a shape slightly different 

 from that in jeffcrsouii, being irregularly triangular in outline, 

 with the angles broadly rounded. On the distal surface, the 

 facets for the cuneiform bones are separated posteriorly by a 

 sharp ridge, while in Leidy's figure* of the navicular of jcffer- 

 sonii they are represented as separated by a groove. 



Two vertebrae are preserved, a caudal and an anterior dor- 

 sal. In the caudal, the vertebral canal is low and broad and the 

 transverse processes, arising from the centrum are directed 

 posteriorly. The epiphyses are wanting and the sub-epiphytic 

 margins are bent inward toward the median plane of the 

 centrum. In the dorsal, the transverse processes are broad and 

 are situated high up on the neural arch, rising above the zyga- 

 pophyses. The spine is short with acute anterior edge. The 

 neural canal is circular. The centrum is not preserved. Below 

 the prezygapophyses, a small, hemispherical process rises from 

 the anterior surface of the neural arch. 



Fragments of several other bones were found, but they are all 

 too incomplete to describe. 



The species is separated from the Californian forms of the 

 same genus described in the present paper by the size of the 

 teeth and the shape of the jaw, in which respect it resembles 

 Megalonyx jeffcrsonii, differing from that species, however, in 

 many skeletal particulars. It has not been identified from the 

 Potter Creek Cave, unless the doubtfully determined specimen 

 referred to Megalonyx jeffersonni can be shown to belong here. 



The specific name refers to the locality, in the foot hills of 

 the Sierra Nevada Range. 



Measurements. 



Length of ramus from anterior extremity of symphysis to 



condyle inclusive 261.5 mm 



Length of lower molar series (M 2 -M 4 ) 63 



Length of symphysis externally 81 



Depth of jaw below M, 75 



Depth of jaw below M 4 70 



Diameters of lower molar crowns not including stalagmite : 

 * J. Leidy, loc. cit. PI. XIII, fig. 8. 



