560 



ZOOLOGY 



SECT, 



produced in front into a short spine or rostrum (r), near the base 

 of which, on the dorsal surface, is the median eye (e). There are 

 five free thoracic segments : the last (ih. 6) bears the genital 

 aperture, and is fused in the female with the first abdominal 



inl.f 



\ 



2-Calocalanus 



FIG. 458. Free-swimming Eucopepoda. 1, female Cyclops, from the right side ; b, dorsal 

 view ; c, antenna of male ; d. swimming-foot, abd.l, first abdominal segment ; an. anus ; 

 ant.l, antennule ; ant.2, antenna ; c. ih. cephalothorax ; e. median 6ye ; en. endopodite ; 



e.s. egg-sac ; ex. exopodite ; ov. ovary ; pr.l, pr.2, protopodite ; r. rostrum; s./. swimming- 

 feet ; th.2, th.6, thoracic segments. (After Huxley, Gerstaecker, Hartog, and Gies 



Giesbrecht.) 



segment (abd. 1). There are four abdominal segments : the last 

 bears the dorsal anus (an), and a pair of caudal styles produced 

 into plumed setae. 



The antennules (ant. 1) are very large, and are the principal 

 organs of locomotion. In the male they are modified (c) by a 



