THE DECAPOD CRUSTACEA. 179 



the smallest. The chelae bear spines, but only on the inner 

 margin of the meropodite and carpopodite (arm and wrist), 

 and the outer margin of the propodite (hand). 



In the spinous Gdlathea (G-. strigosa) the rostrum has 

 only three teeth on each side, and the great claws bear 

 numerous spines on both margins. The two species are 

 very neatly distinguished by the structure of the maxilli- 

 pedes, as will be seen on reference to the table at the end of 

 the chapter. 



The next forms to be considered after Galathea are the 

 little porcelain -crabs, very different in appearance from 

 G-alathea, less active and less beautiful, but no less interest- 

 ing. As already indicated, the porcelain-crabs are sometimes 

 widely separated from Galathea, 

 but we shall consider both here as 

 belonging to the same family 

 (Porcellanidse), for they seem to 

 be closely related. 



We have two British species of 

 Porcellana, both very abundant, 

 and occurring on the shore rocks. 

 The larger, P. platycheles, is to be 



SOUght under Stones in muddy FIG 52. Hairy porcelain-crab 

 nnnlcj TliP rra'h r!r,P nnf UVP in (Porcellana platycheles). The tail 



pools. me crab does not live in isinthe na turai position, that 



mud, SO that the Stones must be is< completely bent beneath 



those which from their position 



have a cavity beneath them, and the likeliest pools are 

 those traversed by a little stream of water. Turn over 

 such stones, and you will see on the upturned surface small 

 muddy crabs with large flattened chelipeds, whose one 

 method of defence seems to be the passive one of crouching 

 down, with the curious great claws, which are densely 

 fringed with hair, arranged at such an angle that they re- 

 semble nothing so much as a flattened pebble adhering to 

 the stone by means of a layer of mud. It is curious that 

 although very common, and found considerably above low- 

 tide mark, these crabs are familiar to very few people. 

 This is partly because the localities which they haunt are 

 not those in which the collector usually lingers, partly no 

 doubt because the habit of crouching down and the coating 

 of inud make them very inconspicuous. 



