156 University of California Publications in Geology [Vol. 7 



ence can be detected between the fossil forms and those of to-day. 

 The presence of the ground-squirrel in both caves indicates 

 that some of the surrounding country during the time of 

 accumulation of the deposits was rather dry and open, although 

 not necessarily low zonally. Now, as then, Citellus b. douglasi 

 can be found associated with C alios permophilus chrysodeirus, 

 Sciuropterus klamathensis, and Sciurus albolimbatus, forms of 

 the Canadian Zone, showing that it has a wide range of habitat 

 as far as temperature is concerned. 



CALLOSPERMOPHILUS CHRYSODEIRUS (Merriam, C. H.) 



Three specimens of this squirrel, all lower jaws, were found 

 in each of the caves, but at a greater depth in Potter Creek Cave 

 than in Samwel Cave. The fragmentary nature of the material 

 makes a subspecific differentiation impossible, and yet the teeth 

 of the specimens from Potter Creek Cave are slightly heavier 

 than in the living species. The specimens from Samwel Cave 

 unfortunately lack teeth. 



EUTAMIAS, sp. 



A portion of a lower mandible without teeth from Potter 

 Creek Cave represents a form of Eutamias, but from this one 

 fragment the specific status cannot be determined. Its small size 

 would place it nearest to Eutamias amoenus. 



SCIURUS GRISEUS FOSSLLIS, n. subsp. 



Type no. 19506, from Samwel Cave. Anterior portion of right 

 lower mandible with P 4 and broken incisor. 



This type, which is the only specimen of Sciurus griseus 

 found in either cave, has such width across the anterior portion 

 of the mandible as to make it strikingly unlike the living forms 

 of griseus which attain their maximum size here in the west, and 

 yet do not approach the fossil form in that respect. The incisor 

 is broken, but the small fragment of it left shows that it is not 

 of especially large size. The P 4 is much worn. It is not larger 

 than that of the living form, but the fact that the mandible is 

 so extremely wide seems sufficient ground for subspecific differ- 

 entiation. It is unfortunate that more material representing 



