. The birds of the Republic of Panama. Birds. 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 it
. The birds of the Republic of Panama. Birds. 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. Please note that these images are extracted from scanned page images that may have
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