16 Oberholser — A New Cliff Swallow from Texas. 



in size very close to the latter. In respect to the color of the forehead, 

 as well, its aberration from lunifrons is in the direction of melanogastra, 

 ■with which also it may be found to intergrade. After due allowance 

 has been made for individual variation which, however, does not exist 

 to an unusual degree, the characters exhibited by this new race seem to 

 be very constant, at least in the considerable series available for exam- 

 ination. 



Apparently all the breeding cliff swallows of southwestern Texas 

 ought to be referred to tachina, the range of which extends thence into 

 eastern Mexico as far at least as Vera Cruz. 



The following average measurements of the three forms of Petrocheli- 

 don here concerned have been kindly furnished by Mr. Ridgway. They 

 relate to males, and are in millimeters. 



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