162 ANIMAL LIFE IN DESERTS 



The difficulty of accepting the view that pale sandy- 

 tints " protect " the nocturnal animals of deserts, is 

 as nothing compared with the difficulty of accepting 

 the same view with regard to certain subterranean 

 forms. The Pocket-Gophers (Thomomys) of the 

 southern United States are found in a variety of 

 environments, including the deserts. They very 

 rarely come above ground, but none the less those 

 that live below the surface of the desert are paler 

 than the others ; the palest of all is Thomomys 

 alhatus described by Grinnell from the Imperial 

 region of California. This form is actually the 

 palest of all the animals of its native region ; and 

 all the mammals of the Imperial region, which 

 is desert but not of an extreme sort, are very 

 pale. It is interesting to learn that the soil in 

 which this Pocket-Gopher burrows is by no means 

 very dry. 



The Marsupial Mole (Notoryctes), which is a purely 

 subterranean inhabitant of sandy places in Central 

 Australia, is pale sandy, frequently almost white, in 

 colour. It is even more rarely exposed to dayhght 

 and to enemies on the surface of the soil than the 

 Pocket-Gopher, and unless we postulate that both 

 are descended from ancestors which Hved on the 

 surface of deserts and there acquired a " protective 

 coloration," we cannot in any way accoiuit for their 

 colour : for such an hypothesis there is not a shadow 

 of evidence. 



Similar examples occur among the Reptilia. The 

 Sand Boa {Eryx jaculus) and the nearly Kmbless 

 Skink {Eumeces scutatus) are animals which live 



