156 ANIMAL LIFE IN DESERTS 



we have already considered as the increased black- 

 ness of the more desert forms of this species is con- 

 fined to the invisible ventral surface. ^ 



I can find few records of the occurrence of black 

 diurnal animals in any desert outside the Palsearctic 

 region : it is possible that black animals occur and 

 that no one has called our attention to them. It is 

 interesting to notice that Merriam refers to the 

 Tenebrionid genera Eleodes and Asima as common 

 and characteristic in the Painted Desert, in America. 

 Hudson speaks of Galictis barbara, a " quaint-looking 

 weasel, intensely black in colour, and grey on the 

 back and flat crown"; this animal is diurnal and 

 hunts in companies on the pampas of La Plata. In 

 the same country is found Didelphys azarce, a black 

 and white oppossum : this animal is also diurnal. 

 It is, of course, possible to suppose that these two 

 totally unrelated conspicuous diurnal predatory 

 animals exhibit " warning coloration," a topic too 

 large to be considered here. 



I have summarized the facts ; let us now see 

 whether they are capable of explanation. Many of 

 us, during our childhood, were taken to the Natural 



1 Among the Amphibia and Reptiles which inhabit deserts 

 there are species which develop brilliant colours in the wet season 

 in such a way that they become extremely conspicuous. This 

 brilliance reaches its climax after pairing has taken place, and 

 is common to both sexes of the frog or lizard concerned. For 

 details consult C. L. Camp, Notes on the Local Distribution and 

 Habits of the Amphibians and Reptiles of South-Eastern California 

 in the Vicinity of the Turtle Mountains, Univ. of California 

 Publications in Zoology, XII, p. 511 (Aug. 12, 1916), and Baldwin 

 Spencer, Report on the Work of the Horn Scientific Expedition 

 to Central Australia, Part I, pp. 26, 27 (1896). 



