W. Rinner 1949 Journal 5 Aug. New Mexico, Otero Co., White Sands Nat'l Monument Morning spent searching dunes for reptiles. Rain the previous day had well soaked the sand to a depth of 12 inches or more and left the sand this morning damp and firm. A footprint in level areas could scarcely be detected and walking up all but the steepest slopes was like walking up a hard-packed earth hill. For air, surface sand and below surface temperatures see R. Stelbrink notes, just about time temp. becoming hot. Bob got first Holbrookia, other animals soon appeared on sun facing slopes of dunes and he got in rapid succession C. perplexus and Sceloporus undulatus. S. undulatus and H. maculata both seen in about equal numbers but perplexus more abundant. Also perplexus is only one seen on darker colored, exposed, underlying soil between dune formations. It was quite conspicuous on such soil. Problem of whether or not these forms gradually darken up at periphery of dunes present itself. Furthermore, is this a result of environmental influence or genetic control? Entire afternoon spent writing up notes in Alamogordo.