R. Zweifel 1953 Journal 9 mi. N Mazatlan, 100'; 500', Sinaloa, Mexico July 12 Dense thorn forest. Relatively level ground, but a few small hills nearby. After dark when a very light rain was falling Bill and I walked along the highway for a couple of hours. Collected were 12 Scaphiopus couchii, 3 Smilisia bandini, 1 Pterostylis fodians and 1 Bufo mazatlanensis. Shortly after our return at about 11:00 PM, a very heavy rain began to fall and continued through much of the night. Our tent shed water like a screen door, making the night most uncomfortable. This afternoon we rigged up a tarp to funnel rain water into a bucket. The rain is heavy enough to fill the bucket in short order. July 13 With a slight let-up in the early daylight hours, the heavy rain continued until almost noon. When the sun came out I walked along a road through the thorn forest until attracted by a frog chorus. The chorus proved to be coming from a dammed up pond and the stream flowing into it. The surface of the pond, about 50' in diameter, was a mass of amplexing and calling Scaphiopus couchii. Bufo mazatlanensis males were calling from the edges of the pond. Their call is a trill which lacks the power and rattling quality,