400 



CRUSTACEA ENTOMOSTRACA. 



dilated oviducts (uteri) contained in a dorsal expansion of the 

 posterior thoracic region. In Cyclops one fertilization suffices 

 for many broods (Hartog). Firm -shelled eggs are produced by 

 Diaptomus towards the end of the reproductive period, and pass 

 through a latent stage before hatching (Wolf). 



Development takes place by means of a complicated meta- 

 morphosis, which, in many parasitic forms, is a retrograde one. 

 The larvae have, when hatched, the nauplius form, with an 



FIG. 262. Metamorphosis of Cyclops, a Nauplius larva of Cyclops sermlatus, after hatching ; 

 b older stage, more highly magnified ; c very young Cyclops form. A anus ; A', A" first and 

 second antennae ; AD rectum ; D intestine ; F',F" first and second swimming feet (second 

 and third thoracic appendages) ; G rudimentary gouads ; He urinary concretions ; Md, 

 Mf mandible ; M x first maxilla ; Mxf maxilliped (partially hiding the second maxiJla) ; 

 01 upper lip ; SD antennal gland. (From Claus.) 



unpaired frontal eye and three pairs of appendages. Hooked 

 setae on the second and third pairs of appendages serve to con- 

 duct the food into the mouth, which is covered by a large upper 

 lip (Figs. 242 and 262, a). The posterior region of the body is 

 destitute of appendages, and terminates with two setae at the 

 sides of the anus ; it includes the thorax and abdomen, which 

 are as yet undifferentiated. The antennary glands act as 

 excretory organs. 



The alterations undergone by the larvae in the course of 



