COPEPODA. 



403 



In Lernaea (Fig. 266) such pigmy males were for a long 

 time vainly sought for upon the peculiarly shaped body 

 of the large female (Fig. 

 266, c, d) which carries 

 egg tubes. At last it was 

 discovered that the small 

 Cyclops-like males (Fig. 

 266, a) lead an independent 

 life and swim about freely 

 by means of their four 

 pairs of swimming feet, 

 that the females (Fig. 266, 

 b), in the copulatory stage 

 resemble the males, and 

 that it is only after copula- 

 tion that they (the females) 

 become parasitic and under- 

 go the considerable increase 

 in size and modification of 

 form which characterizes 

 the female with egg-tubes. 



Monstrilla and its allies 

 pass through a very re- 

 markable life-history. The 

 adult forms are pelagic 

 animals, destitute of alimen- 

 tary canal, mouth parts 

 and second antennae. The 

 nauplius attaches itself to 

 the bodies of sedentary Poly- 

 chaetes, and casting off its 

 appendages penetrates into 

 the vascular system of the 

 host, in which all further 

 stages 'in the development 

 supervene, though without 

 casting a skin (Malaquin*). 

 Nourishment is taken in by means of the second antennae and 



Sp 



FIG. 265. The two sexual animals of Chon- 

 dracanthus gibbosus magnified about six 

 diameters, a Female seen from the side ; b 

 from the ventral surface with adhering males : 

 c male strongly magnified. A eye ; An' 

 anterior antennae ; An" posterior antennae 

 (for attachment) ; D intestine ; f, F" the two 

 pairs of thoracic feet. M mouth parts ; Oe 

 oesophagus ; Ov egg-tubes ; Sp spermato- 

 phore ; T testis ; Vd vas deferens. From Claus. 



* Malaquin, Le parasitisme evolutif des Monstrillides, Arch. Zool. exp. 

 3, T. 9, p. 81. 



