28 Proceedings of the Biological Society of Washington. 



parts. The female of Sialia sialis cpiscopus differs from the female of both 

 Sialia sialis fulva and Sialia sialis guatemalae in the much darker lower 

 surface ; and from the female of Sialia sialis sialis in the more greenish 

 tone of the blue on the upper parts and also usually in the somewhat 

 lighter tone of the anterior under surface. As in the other races of this 

 species, there is considerable individual variation in the color of the blue 

 on the upper surface, and this is exemplified by a male ( No. 241,189 

 U. S. N. M. ), which has the blue decidedly darker and more purplish 

 than in the type. Specimens from Fort Clark, Texas, and from El Blanco 

 on the Lower Rio Grande in Texas, belong also to this new race. 



Detailed measurements of the good plumaged adults of Sialia sialis 

 episcopus now available are as follows: 



a> 

 a 



