1914] Grinndl: Mammah and Birds of the Colorado Vallcij 20:} 



being very broad, tending to cover in some eases the whole pileinn. 

 though becoming concealed beneath an olive wash posteriorly, and 

 with a mixture of yellow. 



Extreme examples of scirpicohi arc conspicuously different from 

 the nearest approach to it in appearance among many specimens of 

 occidentalis from Nevada, northern California, British Columbia and 

 southeastern Alaska. But among the considerable number of speci- 

 mens from the range of scirpicola, there are some which have so far 

 defied every effort to distinguish them satisfactorily from occidentalis. 

 The problem is complicated by the fact that there are yellowthroats 

 moving through the range of srirpirola at the same season that the 

 resident birds are nesting, that is. iinlil the last week in April at least. 



The twelve Colorado Valley c.\am[)lcs referred to scirpicola (char- 

 acterized by (Iriimcll. IIUII, p. ()5) are listed in an accompanying table 

 to sliovv locality and date of capture, and measurements. One speci- 

 men, no. 13723, deserves special comment because of an extraordinary 

 aberrancy in coloration : the whole throat is clear, intense cadmium 

 yellow, in marked contrast with the normal canary yellow of the chest 

 and remaining lower parts; otherwise the bird is like the average. 

 This extra intensification towards orange, though over a restricted area, 

 is pi'<)1)ably a cnhir change of significance along the same line as <lis- 

 cussed in this paper under dolaptes chrysoides. 



The tule yellowthroat was closely restricted to dense vegetation 

 growing close beside or over water. Tules 1)ordering sloughs formed 



MEASUREMENTS IN MILLIMETERS OF GEOTIILYPIS TEICBAS SCISPICOLA 

 PROM THE COLORADO VALLEY 



Mus. No. Se.x Localit.v Date Wing Tail Tarsus Culmen 



Riverside Mt., Calif, side 

 Riverside Mt., Calif, side 

 Ehrenberg, Ariz, side 

 5 mi. N. Laguna, Ariz, side 



4 mi. S Potholes, Calif, side 



5 mi. N.E. Yuma, Calif, side 

 5 mi. N.E. Yuma, Calif, side 

 5 mi. N.E. Yuma, Calif, side 

 Near Pilot Knob, Calif, side 

 Near Pilot Knob, Calif, side 



Average of the males. 



Opposite Cibola, Calif, side 

 4 mi. S. Potholes, Calif, side 



