VOL. XIII, PP. 25-31 MAY 29, 1899 



PROCEEDINGS 



OF THK 



BIOLOGICAL SOCIETY OF WASHINGTON 



DESCRIPTIONS OF NEW BIRDS FROM NORTHWESTERN 



MEXICO. 



BY E. W. NELSON. 



The birds here described were obtained during the past few 

 months by Mr. E. A. Goldman while making collections in west 

 ern Mexico for the Biological Survey of the U. S. Department of 

 Agriculture. A number of birds from southwestern Sonora show 

 closer relationship to forms peculiar to the Cape St. Lucas region 

 of Lower California than to races of the same species in south 

 ern Arizona. This is well illustrated by several House Finches 

 from Alamos, Sonora, which are scarcely distinguishable from 

 typical Carpodacus mexicanus ruberrimus from Lower California. 

 This interesting relationship between the birds of the mainland 

 and those of the peninsula is somewhat similar to that which 

 exists between certain species found near San Bias, Tepic, and 

 their representatives on the Tres Marias Islands. 



In addition to the birds named in the present paper, several 

 others have been described from Sonora, south of Guaymas. 

 These are Mr. Brewster's Psittacula cyanopyga pallida, Thryophilus 

 sinaloa dnereus, and Polioptila nigriceps restricta (Auk, VI, pp. 

 85-98, 1889), and Callipepla gambeli fulvipectus Nelson (Auk, 

 XVI, pp. 26-27, 1899), all from Alamos. The result of the com 

 paratively small amount of work on the birds of this region 

 seems to indicate the existence there of a minor faunal area of 

 comparatively limited extent. 



I am indebted to Mr. Robert Ridgway, curator, and Dr. Chas. 

 W. Richmond, assistant curator of birds, in the National Mu 

 seum, for continued courtesies during the preparation of this 

 paper. 



8 BUM.. Soc. WASH., Y..I,. XIII. IS'.i'.i (25) 



