CRUSTACEA OF THE SEASHORE 109 



described, strongly suggests, however, that conceal- 

 ment from sight is an important protection to some 

 shore Crustacea, and helps to make it probable that 

 the same end is reached in other cases by modifica- 

 tions of form and colour. 



There can be no doubt, at all events, that many 

 Crustacea are very inconspicuous to human eyes 

 when they remain motionless in their natural sur- 

 roundings. Thus, for example, the Caprellidae, or 

 " Skeleton Shrimps " (see Fig. 22, p. 54), are hard to 

 detect without very close search, as they cling to the 

 feathery branches of the hydroid zoophytes among 

 which they are usually found. They are strangely 

 modified Amphipods, in which the body is slender 

 and thread-like, and generally of a semi-transparent, 

 whitish or yellowish colour, like the zoophytes on 

 which they live. They clamber about among the 

 branches with a movement like that of a " looper " 

 caterpillar, and often remain clinging by means of 

 the hooked claws of the hinder pairs of legs, with 

 the fore part of the body gently waving about. 



The little Crabs of the family Leucosiidae (Oxy- 

 stomata), of which the British representatives are 

 several species of the genus Ebalia, are often ex- 

 tremely like pebbles of the gravel among which they 

 live. In many tropical species the carapace is pitted 

 and eroded, so as to resemble a worn fragment of 

 coral shingle. One of the most striking cases among 

 the Crabs, however, is that of Huenia proteus 



