212 PRIMARY FACTORS OF ORGANIC EVOLUTION. 



over the series of nauplius forms [which are traversed 

 by other copepods] and the larva, as soon as hatched, 

 undergoes a moult, and appears at once in the youngest 



Cyclops form with 

 antennae adapted 

 for adhering, and 

 mouth -parts for 

 piercing. From this 

 stage they under- 

 go a retrogressive 

 metamorphosis, in 

 which they become 

 attached to a host, 

 lose more or less 

 completely the seg- 

 mentation of the 

 body, which grows 

 irregular in shape, 

 cast off their swim- 

 ming feet, and even 

 lose the eye, which 

 was originally pres- 

 ent (Lernceapoda). 

 The males, how- 

 ever, in such cases 

 often remain small 



Fig. 52. Lerncza branchialis ; a, male ; , non- ^nd dwaried, and 



degenerate female; c, female after fertilization adhere frequently 

 undergoing metamorphosis ; d, do. with egg sacs, , 



natural size. From Claus. Ore than One, 



firmly to the body 



of the female in the region of the genital opening. In 

 the Lerncea such pigmy males were for a long time 

 vainly sought for upon the very peculiarly shaped body 

 of the large female (Fig. 52), which carries egg-tubes. 



