12 



THE LIFE OF CRUSTACEA 



brush-like structure, which is one of the gills. In 

 the natural position the epipodite and its gill lie in 

 the gill chamber, hidden from view by the side-flap 

 of the carapace. 



The legs (Fig. 4) can, without difficulty, be seen 

 to consist each of seven segments like those of the 



maxillipeds, but there 

 is no exopodite. In the 

 young Lobster, when 

 just hatched from the 

 egg, however, each of 

 the legs has a large 

 exopodite like that of 

 the third maxilliped. 

 These exopodites, which 

 are used in swimming, 

 are afterwards lost as 

 the animal grows ; but 

 their presence in the 

 young is interesting as 

 confirming the conclusion that the legs, like the 

 maxillipeds, are built on the same plan as the swim- 

 merets. The large claws, and also the first and 

 second pairs of walking legs, end in pincers, or chelc^, 

 the penultimate segment projecting in a thumb-like 

 process against which the last segment works. Each 

 leg, except those of the last pair, has on its first 

 segment an exopodite with a gill like those of the 

 maxilliped. 



Fig. 



4 — Walking Legs 

 Lobster 



A, Of first pair ; B, of third pair 



