K. Selander, 1954 C. humilis and nigricaudatus 20 SE Tonalá, Chiapas, Mexico March 25 Drove directly to a point 2 mi. SE Oxilapa early in the morning. In a patch of cut trees we found perhaps 10-12 C. nigricaudatus x humilis individuals. They were foraging in small trees around edges of cut-over forest area and on the large tree trunks and branches of the trees. I judge that this area (almost 3/4 city block in area) was cut sometime this year as the wood was still clean where cuts had been made. One pair we watched for some time near the part of the cut-over area adjacent to the road. The two birds were foraging close together and almost invariably moved about together. On one occasion one of these two birds chased another worm through the tree (in the area the pair had been frequenting) in a chase which looked as if it were a territorial defense. While the chase was in progress both birds seemed to be calling excitedly, while the third (the female?) remained quietly perched on a low branch in the area. After the chase one bird involved returned to the area and sang a song. Whenever the pair moved from one place to another they sang almost immediately after - and often they began the song on the wing just before arriving at their new perching place. On several occasions I heard one bird sing while the other gave a fast series of gorbled caws. I believe this is of common occurrence.