130 MOSTLY MAMMALS 



that such modifications of colour, especially when they 

 occur in animals belonging to many widely sundered 

 groups, cannot have taken place suddenly, but must have 

 been due to very gradual changes as the particular 

 species adapted itself more and more completely to a 

 desert existence. 



To obtain an idea of the type of coloration character- 

 istic of the smaller desert animals, the reader cannot do 

 better than pay a visit to the Natural History branch of 

 the British Museum, where, in the Central Hall, he will 

 find a case devoted to the display of a group from the 

 Egyptian desert, mounted, so far as possible, according 

 to their natural surroundings. 



Among such animals may be mentioned the beautiful 

 little rodents respectively known as jerboas and gerbils, 

 together with various birds, such as sand-grouse, the 

 cream-coloured courser, the desert-lark, desert-finches, and 

 desert-chat, and also various small snakes and lizards, 

 among the latter being the common skink. Although 

 some of the birds retain the black wing-quills of their 

 allies, in all these creatures the general tone of coloration 

 is extremely pale, browns, fawns, russets, olives, greys, 

 with more or less of black and pink, being the pre- 

 dominant tones ; and how admirably these harmonise with 

 the inanimate surroundings one glance at the case in the 

 Museum is sufficient to demonstrate. Very significant 

 among these are the desert-finches (Erythrospiza\ which 

 belong to the brightly coloured group of rose-finches, 

 one of these specially modified species ranging from the 

 Canaries through the Sahara and Egypt to the Punjab, 

 while the second is an inhabitant of the Mongolian desert. 

 Among larger animals, a considerable number of the 

 gazelles are desert-dwellers, these including the palest- 



