198 



antennae pronouncedly prehensile, terminating in a very movable claw, and 

 more strongly developed in female than in male. Oral parts, as in the Cory- 

 cceidce, densely crowded on a protuberance of the ventral face, placed far 

 behind the insertion of the antennae. Maxillae and anterior maxillipeds very 

 small and clawed at the extremity. Posterior maxillipeds wanting in female, 

 normally developed in male. Natatory legs comparatively feeble in structure, 

 with the rami more or less incurved. Last pair of legs small, but well defined, 

 uniarticulate. Ovisacs in female of very large size. 



Remarks. This family also is here taken in a more restricted sense 

 than done by most other authors. Thus I find it necessary to remove the 

 genus Bomolochus of Nordman, which is generally included in the present 

 family, but which seems to me to differ in many points so materially from 

 the other genera, that it scarcely can be associated with them. In the restriction 

 here adopted the family as yet only comprises 3 genera, viz., Ergasilus Nordman, 

 Ergasiloides G. O. Sars and Thersetina Norman (Thersites Pagenstecher). Only 

 the first-named genus is as yet stated to be represented in the fauna of Norway. 



Gen. 48. Ergasilus, Nordman, 1832. 



Generic Characters. Body of adult female more or less pyriform in 

 shape, with the anterior part greatly tumefied and the segments not very 

 sharply marked off from each other; that of young female (before affixion) 

 and of male pronouncedly depressed and tapered behind, with all the segments 

 sharply defined. Tail comparatively short, and composed in female of 4, in 

 male of 5 segments. Anterior antennae 6-articulate and densely setiferous. 

 Posterior antennae in female exceedingly powerful, 3-articulate, terminal joint 

 together with its apical claw forming a very strong and movable dactylus 

 admitting of being bent against the preceding joint; those in male much 

 smaller, but of a similar structure. Maxillae armed at the extremity with a 

 movable claw-like spine accompanied by a short seta, and having moreover a 

 somewhat similar spine outside at some distance from the tip; palp small, 

 lamelliform. Anterior maxillipeds terminating in a single claw-like spine densely 

 hairy on the edges. Posterior maxillipeds wholly absent in female, but well 

 developed in male and terminating in a slender clawed hand. Natatory legs 

 with the rami comparatively short and 3-articulate, except the outer ramus of 



