THE COLOURS OF DESERT ANIMALS 165 



moperdix heyi) and the See See (A. griseogularis) 

 are two small Partridges with exquisite soft buff and 

 greyish sandy feathers. All through the middle of 

 the day they lie up in holes in rocks and under 

 boulders : at the time they are, of course, invisible 

 owing to their position, not their colour. When the 

 sun is low they come out to feed ; though their legs 

 are short their shadow is long at this time of day, 

 and they are quite conspicuous. 



In certain grasshoppers it seems probable that 

 the coloration is actually protective. Vosseler men- 

 tions the Short-horned Grasshoppers Eremobia, 

 Eremocharis, Pamphagus and others, in all of which 

 the thorax and abdomen are widened and flattened 

 in such a way that the animal is triangular in 

 transverse section and flat below. When it presses 

 its ventral surface to the ground there is no shadow 

 to betray it, and while at rest it carries the broad 

 flat femora pressed against the abdomen, thus 

 contributing to the same result. In this attitude 

 every visible part of the insect is "desert colour," 

 and is roughened so that it resembles rough rock or 

 sand : bright colours occur on the hind-wings, on 

 the inner face of the femora, and on intersegmental 

 membranes, but they cannot be seen while the 

 insect is at rest. It seems, then, that in these 

 grasshoppers shape, colour, surface sculpturing and 

 habit co-operate to render the insect difficult to 

 see, and one must admit that in these cases the colour 

 is protective, for it is unreasonable to argue that the 

 shape, sculpturing and habit are protective, and 

 that the colour with which they co-operate is due to 



