I A.& Ridgway, Geographical Variation in Sialia mexicana. f A ' 



Auk 

 ril 



across the anterior portion. Among 34 specimens from Wash- 

 ington, Oregon, California, and the western edge of Nevada only 

 6 are of this character, the remainder having the chestnut of the 

 back separated into two lateral patches, barely coalescing for a 

 slight extent in a few specimens only, and often reduced to two 

 widely separated and greatly restricted areas. The six excep- 

 tions are 1 from Fort Tejon (August 7), 1 from Walker's Basin 

 (November 5), 2 from Berryessa (November 14 and December 

 8), 3 from Santa Isabel, San Diego Co. (December 29 and Feb- 

 ruary 15), 1 from Murphy's, Calaveras Co. (winter), and 1 from 

 San Francisco. The latter is without date, but is in spring or 

 summer plumage; and being obtained from a dealer's stock ma)' 

 well be ignored. The others are all fall or winter specimens, 1 

 and, except that from Murphy's, from southern California, may 

 have been migrants from the eastward. 



The type of Sial/'a occidentalis Townsend is a bird of the 

 western style, with perhaps a little more than the average amount 

 of chestnut on the back. Whether the type of S. cceruleocollis 

 Vigors was also a representative of this style probably cannot 

 now be determined, neither the description 2 nor colored figure 

 being sufficiently accurate to permit positive identification, while 

 nothing whatever is said as to its locality. 



While hesitating to formally separate the Rocky Mountain 

 bird I believe it will yet be found necessary to do so ; and in 

 view of this probability would suggest for it the name Sialia 

 mexicana dairdi, 3 in respectful memory of Professor Baird, as 

 well as a proper recognition of his discovery of the geographical 

 variations refen-ed to. 4 



1 The one from Fort Tejon, although taken in August, had nearly completed the fall 

 moult. 



2 See foot-note on page 155. 



3 Type, No. 7637, U. S. National Museum, Camp no, New Mexico, Jan. 31, 1854; 

 Kennerly <x Mollhausen. 



4 Since the above was written I find on reference to some memoranda which I 

 made concerning specimens not now available for examination, that among speci- 

 mens previously examined were the following having the back wholly chestnut : 

 Beaverton, Oregon, 2; Wilson's Peak and Alhambra, southern California, 3. On 

 the other hand, among those with the back only partly chestnut were the following : 

 Beaverton, Oregon, 13; Wilson's Peak and San Diego, California, 1 each; Granite 

 Gap, New Mexico, I. 



