IN 1932 Bradt described the mammals of the black lava Malpais of the Tularosa Basin in New Mexico and noted the close approximation between the colors of the animals and of the surrounding rocks. In the same year Benson described several new dark colored rodents from the lava, and Dice and Blossom in 1939 summarized the relationships between soil and pelage colors in the mammals of this and numerous other areas of the desert southwest. The latter authors demonstrated the general rule that dark colored forms were correlated with dark soils, while pale forms were correlated with light soils. In the Malpais, they found five species of mammals that tended toward dark coloration. In the contiguous snow-white gypsum dunes of the White Sands National Monument, they noted three species of mammals with pallid pelage tones. In less distinctively colored areas, mammals tended to approach the reds, yellows, buffs, and browns of their native substratum. Smith (1943) has described the pale lizards of the White Sands (Uta stansburiana stejnegeri Schmidt, Sceloporus undulatus consobrinus Baird and Girard, Holbrookia maculata ruthveni Smith, and Cnemidophorus perplexus Baird). Color notes on the reptiles from adjacent normal colored regions are readily available. The reptiles of the Malpais have not been studied, and in order to examine their colorations, three collecting trips were made across various portions of the lava in 1948. Color notes were made in the field. Comparative studies were made, largely, from preserved material. The Malpais of the Tularosa Basin consists of about 120 square miles of recent vesicular dull black lava extending north and south in a narrow irregular strip about 44 miles in length. It is bordered by arid plains and hills which determined the shape of the flow and which now bear the flora and fauna of the Chihuahuan biotic province. The lava is exceedingly rough and almost impassable. In places it is 50 or more feet in thickness. The surface displays such features as secondary terraces, collapsed bubbles and flow channels, pressure domes, knife-like ridges, extensive crevasses, crumpled and up-thrust extrusions, pahoehoe formations, cinder cones, and at the northern end a low crater. The surface is weathered but little. Enough glassy edges remain to damage even the heaviest boots. The violent winds of this part of the continent have buried the northern toe of the beds in drifted sand and loess. They have also carried into the lava sufficient pockets of soil to support a sparse growth of desert plants. In the northern portions (elevation about 5300 feet) ephydra and small junipers dominate. Farther south the more prominent large plants are mesquite, cholla, prickly pear, sotol, lecheguilla, atriplex, and near Malpais Spring (4150 feet) at the southern end of the beds, large Allenrolfia shrubs.