FAMILY HIRUNDINIDAE 



37 



found in montane regions and ruficollis at lower elevations. There 

 are localities where they evidently form mixed colonies without inter- 

 grading, although it would seem that specimen evidence for lack of 

 intergradation at these sites is scant. The problem remains with what 

 to do with the form decolor, which has a rather circumscribed range, 

 being found along the southern half of the Pacific coast of Costa 

 Rica south and east in Panama to Veraguas. Stiles recognized decolor 

 as a subspecies of Stelgidopteryx ruficollis, but its characters are 

 exactly those one would expect of intergrades between ruficollis uro- 

 pygialis and serripennis; such an interpretation is reinforced by the 

 great variability observed in decolor. Based purely on museum speci- 

 mens, one could argue that serripennis and ruficollis represent former 

 isolates that in coming in contact along the Pacific Coast have formed 

 a hybrid zone (there apparently are no pure parental types in the range 

 of "decolor") , whereas in their area of contact in the montane regions 

 of the Atlantic slope they perhaps behave differently. More fieldwork 

 and collecting will definitely be needed before this problem can be re- 

 solved satisfactorily. S. L. O.] 



Figure 3. — Portion of outer primary feather of the Rough-winged Swallow, 

 Golondrina Ala de Sierra, Stelgidopteryx ruficollis, showing hooklike leading 



barbs. 



STELGIDOPTERYX RUFICOLLIS SERRIPENNIS (Audubon) 



Hirundo serripennis Audubon, Orn. Biogr., vol. 4, 1838, p. 593. (Charleston, South 

 Carolina.) 



Characters. — Throat grayish white; rump and upper tail coverts 

 grayish brown concolor with back; pale edgings on secondaries re- 

 duced in extent, and darker, less definitely white; upper surface some- 

 what darker; wings dull black; tail brownish black. 



Measurements. — Males (10, taken in the breeding range, March to 



