"R. Zweifel 1953 Eleutherodactylus 7 mi. SW El Vergel (Yogurita) 7800', Chichualna, Mexico 2290 RZ June 30 Calling from a crack in a boulder shortly after nightfall. The call is a monoregular quack, resembling that of Hyla arenicolor. The dorsal surface of the frog is pale green with numerous darker spots, the spots being dark gray. The resemblance to the lichen-encrusted rock is close. Even the iris is green. The frog gave a very few isolated calls yesterday. This evening, following this afternoon fairly heavy showers, it called regularly. The nearest surface water is the stream 100 yards away. 2334-5 RZ July 2 This afternoon we had our first heavy rain since we have been here, probably the first heavy rain of the season. In the evening several frogs were heard calling. We collected them. I found a male calling from a crack in an outcropping boulder and found a large female hopping across a rock for toward the male. At least ten frogs were heard. The call carries for several hundred yards. All frogs that were tracked down were either in rocky outcrops or on boulders nearby.