1912] 



Kellogg: 



Pleistocene Rodents of California 



163 



// 



Fig. 11. Erethison epixanthum. Inferior view of skull, no. 11276, X %. 



the auditory bullae seemed to be unusually long, anteropos- 

 teriorly, and inflated, but it is that of a young individual, and it 

 seems to be a fact that the bullae shrink and contract with age, 

 so that the general shape of the bullae rather than their size 

 would constitute a dependable character and, in this case the 

 form of the bullae of the fossil specimen is similar to that of the 

 living species. Even such a small series of skulls of the living 

 species showed so much variation that no comparative measure- 

 ments are given. 



Measurements op Specimens from Samwel Cave 



No. 11276 No. 8901 



Length of skull from anterior face of incisors to back 



of occiput 107.5 mm. 



Anteroposterior diameter of bullae 21.2 19. 



Transverse diameter of bullae 14.2 12.4 



LEPUS CALIFORNICUS Gray 

 There are about two dozen specimens consisting of lower 

 mandibles and two portions of skulls from Potter Creek Cave 

 referable to this species. There are some slight points of differ- 

 ence, however, in the fossil forms, such as proportionately great 

 length of the lower tooth row and diastema in relation to the 

 size of the mandible. The upper tooth row is slightly longer, 

 and the anterior width of the incisive foramina somewhat greater 



