94 



THE CRUSTACEA 



increase in size, in some cases, to several times the length of the 

 body, and as the cuticle covering them is very thin it is believed 



11 — ovj. 



■--f. 



Fig. 53. 



Staj^es ill the life-history of Hacmoccm danac. A, free-swininiiiig uauplius-larva, x -280. B, 

 embryo after penetrating into the body-cavity of the host; no organs remain except tlie 

 degenerating nauplius-eye. C, later stage, from the vascular system of the host ; the alisorptive 

 processes have begun to develop. D, still later stage ; the absorptive processes are fully 

 formed and the posterior end of the embryo is provided with rows of recurved hooks. E, the 

 adult female, just before emergence from the host ; the anterior part of the body is distended 

 with eggs. P, free-swimming female, carrying the (>\truded eggs, x 28 ; the hypodermis in the 

 anterior part of the body has separated from the cuticlr altir expulsion of the eggs and forms 

 a sheath around the nerve-cord, a!, anteimule ; /</ . luaiii ; r , nauplius-eye ; /, swimming-feet ; 

 ff.s, genital setae ; ni, position of mouth ; md, mandible of naui)lius ; n, nerve-cord (■(iiinecting 

 brain with ventral nerve-chain ; ov, mass of eggs carried on genital setae ; oc.i/. ovary ; in-, 

 absorptive processes. (After Malaquin.) 



that they act as absorptive organs. In some cases, but not ahvays, 

 a second pair of these processes is found behind the first. From 

 the position which they occupy relatively to the rudiments of 



