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asstethasks. Posterior maxillipeds distinctly developed; propodos rather narrow 

 and quite nacked; dactylus long and slender, evenly curved in its outer part. 



Colour in both sexes an uniform opaque white. 



Length of adult female attaining 3.30 mm.; that of male only 1.60 mm. 



Remarks. The most conspicuous peculiarity distinguishing the above 

 -described Copepod is perhaps the strongly marked lateral protuberances of 

 the cephalon in the female, giving the body, as it were, a somewhat hammer- 

 shaped form ; hence the specific name here proposed. Moreover the peculiar 

 curvature of the ovisacs distinguishes this form from most other Copepoda. 



Occurrence. I have found this remarkable Copepod occasionally within 

 the pallial cavity of a species of Necera (N. obesa) taken off the west coast 

 of Norway. As the parasite is of rather large size in proportion to its host, 

 it could be easily detected even to the nacked eye as an opaque white mass 

 shining through the pellucid valves of the shell. No doubt the parasite is 

 very noxious to the Mollusk, and in all probability quite destroys its repro- 

 ductory faculty. 



Fam. 16. Eunicicolidae. 



General Characters.- Anterior division of body large, shield-like, with 

 the segments more or less completely fused together dorsally, those of posterior 

 division well defined. Anterior antennae attenuated; posterior ones sub-prehen- 

 sile. Oral parts rather peculiar in structure, though present in the normal 

 number. Legs imperfectly developed, the 2 posterior pairs being wholly absent. 

 2 ovisacs present in female attached laterally. 



Remarks. This new family is established, to include the remarkable 

 genus Eunicicola of Kurz (= Eurynoliis Scott), the very aberrant characters 

 of which prevent its reception within any of the other families here recorded. 

 The description given by earlier authors (Kurz and Scott) could even leave some 

 doubt about the right position of this genus within the section of the poeci- 

 lostomous Cyclopoida, as here defined. On a careful examination of the oral 

 parts, however, I have found that, in spite of their rather aberrant structure, 

 they in reality are built on the type characteristic of that group of Copepoda. 



