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 



f. 



FIG. 53. 



Stages in the life-history of Haemocei-n datutc. A, free-swimming nauplius-larva, x 280. B, 

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

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

 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, tlm 

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

 with eggs. F, free-swimming female, carrying the extruded eggs, x 28 ; the hypodermis in the 

 anterior part of the body has separated from the cuticle after expulsion of the eggs arid forms 

 a sheath around the nerve-cord. ', antennule ; br, brain ; e, nauplins-eye ; /, swimming-feet ; 

 <7.s, genital setae ; m, position of month ; mil, mandible of nauplius ; n,' nerve-cord connecting 

 brain with ventral nerve-chain ; or, mass of eggs carried on genital setae ; ovy, ovary ; jn; 

 absorptive processes. (After Malaqiiin.) 



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

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

 the position which they occupy relatively to the rudiments of 



