1A.6 Ridgway, Geographical Variation in Sialia mexican a. | A 



Auk 

 pril 



obtained, and for 9 of these I am indebted to Dr. C. Hart Merriam, 

 Chief of the Division of Economic Ornithology, Department of 

 Agriculture, the National Museum collection containing a single 

 specimen only. Although so small, numerically, this series is 

 highly important, as showing that the resident birds of southern 

 Mexico alone are entitled, unqualifiedly, to the name Sialia niex- 

 icana, a fact which would not have been evident without them. 1 

 The number of specimens examined in connection with this 

 paper and the sources from whence obtained are shown in the 

 following: tables : — 



I. Sialia mexicana Sw. 

 II. S. m. occidentalis (Towns.). 

 III. S. m. anabelse Anthony. 



Total, 



A. W. Anthony. — 



National Museum. 1 



Division of Ornithology. 9 



H. W. Henshaw. — 



Total, 10 



The conclusions reached after very careful examination and 

 comparison of the large number of specimens examined may be 

 summarized as follows : — 



(1) Although the Sialia mexicana of Swainson was plainly 

 based on a specimen (from the "tableland of Mexico") having 

 the back entirely blue, the series of specimens from southern 

 Mexico, though small, is sufficient to show that such is by no 

 means a constant — probably not even usual — character of the 

 Mexican form. But these southern resident birds, besides aver- 

 aging considerably larger than any others, are of a much deeper 

 or darker, more purplish, blue color, and the females, at least, 



1 The northern and southern forms were, however, duly separated in 1881 by Mr. 

 Henry Seebohm, in Volume V of the 'Catalogue of Birds in the British Museum' (pp. 

 331-333), though one of the supposed differential characters proves to be altogether 

 unreliable. 



