1912] Grinnell: The Bighorn of the Sierra Nevada 151 



operated as a more efficient barrier to the distribution of Boreal 

 forms north and south than the Pitt River or Feather River 

 gaps to the south, or both the latter combined. 



A pertinent query would lie as to the geographic relation- 

 ship of sierrae with nelsoni. The latter was described (Merriam, 

 1897, p. 218) from the Grapevine Mountains, Nevada, just over 

 the state line from California, adjacent to Inyo County. In an 

 air line the type localities of sierrai and nelsoni are less than 

 95 miles apart. The possibility suggests itself that the same 

 individuals can easily wander back and forth between the desert 

 ranges and the high Sierra Nevada, and may have done so in 

 recent times. 



First, to establish the distinctness of actual topotypes of 



nelsoni from sierrae, request was made of H. W. Henshaw, Chief 



of the Bureau of Biological Survey, for the loan of topotype 



material. This was freely granted, with the result that two out 



of the very series upon which .Merriam based his description. 



have been available for comparison at this Museum. These 



en ■ l i n n wi 28384 



specimens are: Skin and skull $, aged three years, no. , uss 



(U. S. Nat. Mus.) ; skin and skull J 1 , aged two years, no.-^x^ 

 (U. S. Nat, Mus.). Both were taken June 4. 1891. As regards 

 pelage they are extremely worn and faded. Our two examples 

 from the Santa Rosa Mountains, of same season, precisely re- 

 semble them in all pelage characters. Enough of the summer 

 pelage is left on one of the Mount Baxter sierrae (no. 16358), 

 to demonstrate that even in summer the alpine and desert forms 

 show the differential features of pelage. Because of the youth 

 of the exact topotypes of nelsoni, nothing is ascertainable from 

 general size or cranial dimensions. But the Museum's five-year- 

 old ram skull and horns (no. 4740) from the Funeral Range, 

 which is merely the southward extension of the Grapevine Moun- 

 tains, making the points of capture not to exceed 25 miles apart, 

 can be considered a practical topotype. And it is identical with 

 the comparable rams from elsewhere on the southeastern deserts. 

 To sum up, there is a desert race of sheep as distinct from the 

 Sierran, and the name nelsoni was based upon examples of the 

 desert form. 



