NATURAL SELECTION 



667 



Fig. 245. Procryptic coloration of species of pocket mice inhabiting adjoining areas in the 

 Tularosa Basin, New Mexico: Perognathus intermedius ater on black lava; Perognathus apache 

 gypsi on white gypsum sands. (Paintings by Allan Brooks from Benson, 1933, by permission 

 of University of California Press.) 



