18 Oberholser — Description of a Neic Vireo. 



green in contrast to the head and nape; the much more yellowish flanks 

 and sides; the rather less purely white under surface; and the decidedly 

 shorter tail. 



Specimens to the westward in the range of Vireo bellii medius indicate 

 intergradation with, pusillus, and taken in connection with hardly typi- 

 cal examples of the latter from extreme western Texas, show pretty con- 

 clusively that to pusillus there belongs a trimomial name. 



Average millimeter measurements of five specimens of each of these 

 three forms are as follows: 



Vireo bellii bellii (Kansas and Illinois): wing, 55.6; tail, 45.8; exposed 

 culmen, 10; tarsus, 18.5; middle toe, 9.8. 



Vireo bellii medius (Texas): wing, 54.1; tail, 46.3; exposed culmen, 9.7; 

 tarsus, 18.5; middle toe, 9.4. 



Vireo bellii pusillus (California): wing, 54.6; tail, 49.6; exposed culmen, 

 9.3; tarsus, 18.9; middle toe, 9.9. 



