1912] Kellogg: Pleistocene Rodents of California 157 



this new form is not available for, judging from the size of the 

 mandible, the skull might exhibit striking and interesting differ- 

 ences in other respects. Measurements comparing the fossil form 

 with the two largest specimens of S. griseus from the collection 

 of the California Museum of Vertebrate Zoology are given below. 



Measurements 



No. 19506 No. 11362* No. 11359* 



Width of mandible at P 4 14.3 mm. 11.8 11. 



Width of mandible at M, 13.7 10.6 10.7 



* Calif. Mus. Vert. Zoology. 



SCIURUS DOUGLASI ALBOLIMBATUS Allen 



This species is scantily represented by two lower mandibles 

 from Samwel Cave and a portion of the skull with some upper 

 teeth from Potter Creek Cave, but the material is sufficient to 

 establish its status under this species. 



SCIUROPTERUS ALPINUS KLAMATHENSIS Merriam, C. H. 



Four lower mandibles, two from each cave, have been referred 

 to this form. This species represents a zone of high altitudes 

 to-day, and seems especially fond of red fir, Abies magnifica, as 

 a habitat, but it has been found as low as 4500 feet elevation, 

 where red firs do not exist. As has been mentioned above it occurs 

 in the same locality with Citellus b. douglasi, so there is no 

 apparent anomaly in their being found together in the caves. 

 Their scarcity, however, and that of the two preceding genera, 

 Arctomys and Callospermophilus, would indicate that these three 

 animals and others which follow {Aplodontia, Neotoma cinerea, 

 and Lepus klamathensis) , all forms of the Canadian Zone, were 

 here probably near their lowest limit of distribution. 



APLODONTIA MAJOR FOSSILIS Sinclair 



This form was described by W. J. Sinclair, 5 the type being 

 a right mandibular ramus from Potter Creek Cave, lacking the 

 coronoid process and part of the angle. The subspecific char- 

 acters given are that the dental foramen is wider transversely 

 than in the living species, that the ridge in front and below the 



s Univ. Calif. Publ. Bull. Dept. Oeol., vol. 4, no. 7, p. 147, 1905. 



