K. Selander, 1954 C. nigricaudatus 51 Tonalá, Chiapas April 6 and also a few shots on some roll around the Rancho where we heard chiacensis. Noted Thryothorus pleurostictus in the deciduous forest. Song: cheap (o chip), chip, chip, chip until —not unlike a song sparrow but with four short opening notes. [Roll 8 has several shots around the Rancho Ocuilapa and Roll 7 in Ocuilapa and part 2 mi. SE Ocuilapa]. April 7 Worked along the Río Agua Dulce. Bonifacio hunted "clove" the wood along the river for a long distance and collected 13 nigricaudatus × humilis. He saw no chiacensis. I walked about 1/3 mile "down" from the road along the river and found several pools of standing water in the several channels of the river. Rich vegetation along the stream — large amates and various trees and vines. (Took several black & white photographs of places where such wrens occur). Nigricaudatus type wrens were abundant along the river, occupying situations similar to those frequented by chiacensis'. However, chiacensis was rare — I met it only about 3 times. About 9 feet up in an acacia two luiclos were 'chawing' cont- inuously together at a nest. I shot a nigricaudatus (lug luid) and a moment later shot a chiacensis in a bush a few feet away. I think that the chiacensis was at the nest with the other wren — perhaps a dispute — or attempt at mating! Later I heard two other