22 BKITISH COPEPODA. 



steps, their full number of joints and perfect develop- 

 ment.* Those parasites which miss the Nauijlius 

 stage are hatched in Cyclops-foYm ; many of the 

 retrogressive species become fixed to some animal, 

 segmentation is lost, limbs and eyes disappear or 

 become atrophied ; the males, often dwarfed, being 

 permanently fixed near the sexual apertures of the 

 female. 



* For details of this process in tlie genus Cyclops, see vol. i, p. 100. 



