29S THE PLACE OE MIMICRY 



On the surface of the ocean it is comnion for 

 animals of all shapes to be protected by their transpa- 

 rency and often by a blue colour : on the desert equally 

 diverse forms are defended by their likeness to the sand. 

 Modification of shape in the direction of flattening 

 occurs in some species. The elimination of shadow, 

 to be described below, is of the utmost importance on 

 such a stronL;l)* lighted surface as the desert. 



The effect of a uniform appearance ma)' be pro- 

 duced b\- a combination of tints in stiirtling contrast. 

 Thus the dark and light stripes of the zebra blend 

 together at a little distance, and ' their proportion is 

 such as exactly to match the pale tint which arid 

 ground possesses when seen b}' moonlight'.' 



b. Special J^ rotative Rescvib lance is far commoner 

 than general, and is the form usually met with on the 

 diversified surface of the earth, on the shores, and in 

 shallow water, as well as in the masses of Ali^ae floatini/ 

 on the ocean, such as those of the Sargasso Sea. 



In these environments the Cryptic Colouring of 

 animals is usually aided by special modifications of 

 shape, and by the instinct which leads them to assume 

 particular attitudes. Complete stillness, and the 

 assumption of a certain attitude also play an essential 

 part in General Resemblance on land ; but in S|)ecial 

 Resemblance the attitude is often highly elaborated, 

 and perhaps more important than any other element 

 in the complex method by which concealment is 

 effected. In Special Resemblance the combination of 

 colouring, shape, and attitude is such as to produce 

 a more or less exact resemblance to some of the objects 

 in the environment, such as a lump of earth, a stone, 

 a leaf or twig, a patch of lichen, or fiake of bark. The 

 animal is not merel\- hidden from view by becoming 

 indistinguishable from its background, as in the case of 

 General Resemblance, but it is mistaken for some well- 

 known object of no interest to its enemy. 



A good example in the shallow seas round our coasts 



' F. Gallon, South Africa, London. 1889, p. 187. 



