374 University of California Publications in Zoology [Vol. 12 



Grizzly Creek, head of Grizzly Creek, head of Rush Creek, Kan- 

 garoo Creek, head of Bear Creek, Castle Lake. 



Callospermophilus chrysodeirus trinitatis Merriam 

 Trinity Golden-mantled Ground Squirrel 



The distribution of this form is given (Merriam, 1901&, p. 126) 

 as "the Siskiyou, Salmon, and Trinity mountains of northwestern 

 California and southwestern Oregon". It is described as being 

 "much larger and darker than chrysodeirus, and [it] never, so far 

 as known, develops the golden mantle which covers the head and 

 shoulders of that species". The average measurements of six speci- 

 mens from the type locality is stated to be " total length, 283 ; tail 

 vertebrae, 100; hind foot, 43". 



On geographical grounds one would expect the golden-mantled 

 ground squirrels of the parts of Trinity and Siskiyou counties 

 covered by our trip to come under this subspecies. Twelve of our 

 specimens, males, from the various localities, average: total length, 

 269.6 millimeters; tail vertebrae, 96; hind foot, 41.3. An average 

 of four specimens, male, of C. chrysodeirus from Mount Shasta, is; 

 total length, 263.7; tail vertebrae, 89; hind foot, 40.7. Seven 

 specimens, male, from near Mount Whitney, east-central Cali- 

 fornia, average : total length, 276 ; tail vertebrae, 94 ; hind foot, 41.4. 

 Three specimens, male, from Independence Lake, Nevada County, 

 California, average : total length, 258 ; tail vertebrae, 78 ; hind 

 foot, 41.3. 



Of the three measurements, that of the hind foot seems to be 

 the most constant, and judging from this feature as an index of 

 size the specimens from these different regions should all be classed 

 under the same species, namely, chrysodeirus. Moreover, many of 

 our specimens show a well-developed golden color to the mantle, 

 and, as already stated, trinitatis was said to lack this mantle color. 

 On the whole, however, I should say that our series is slightly 

 darker than those from Mount Whitney and Independence Lake, 

 and this, even if other ascribed characters fail, might in itself 

 justify the recognition of a form from the Trinity region. Further 

 study of relevant material, with particular attention to changes 

 of pelage with season, and a greater number of measurements of 

 both body and cranium, may show that there are not sufficient 

 grounds for recognition of a form trinitatis. 



