21 July Continued west on the road to El Novillo Son, where the Mazatan road crosses the Rio Yagui. Had lunch and then spent the rest of the day working the area south of the bridge and east of the river. There is a gravel sorting business over much of the area, hence there are extensive piles of sorted gravel cleared vegetation. Otherwise there is a flat pasture land to some farm land higher up from the river proper. Very close to the river there are several isolated pools of water trapped in the bedrock. Day was cloudy. During both the afternoon and evening we got a Saw the following: E side of Rio Yagui, just south of El Novillo Son Bufo mazatlanensis: all of the larger specimens were seen only on the sandy bank next to the river. None were seen on the gravel banks along the river. There were, however, thousands of newly hatched toadlets that were probably the species, along the banks of the river - both sandy, gravelly bank or near the pools in the bedrock. 367-369 Scaphiopus couchi: seen only on the gravel terrace above the river. Other heard calling at night. 370-375 Pternochyla todensis: many seen and heard around the pools in the exposed bedrock along the river.