30 



from that in female by the presence of an additional seta attached inside the 

 others. 



Body semipellucid, of a whitish colour, with a very faint yellowish or 

 greenish tinge. Ovaria and ova in the ovisacs generally of a dark blue colour. 



Length of adult female 0.75 mm. 



Remarks. This form was first recorded by Lilljeborg under the name 

 of Cyclops magniceps, but was rather imperfectly described, and, as moreover the 

 number of joints in the anterior antennae were erroneously indicated to 8, instead 

 of 6, the species was not recognised by subsequent authors, who generally recorded 

 it under the specific name ceqvoreus proposed by Fischer several years afterwards. 

 The form named by Boeck Cydop christianiensis is also unquestionably the same 

 species. It is distinguished from the nearly-allied form H. propinqvus G. 0. Sars 

 by the more produced caudal rami, as also by its larger size. 



Occurrence. I have found this form not unfrequently in the uppermost 

 part of the Christiania Fjord, where it occurs close to the border of the 

 shallow creeks in the immediate neighbourhood of the town. It also occurs 

 in other places, both of the south and west coasts of Norway, partly in more 

 or less brackish water. 



Distribution. Kullaberg, coast of Sweden (Lilljeborg), British Isles (Brady), 

 coast of France (Canu), Algeria (Richard), Madeira (Fischer). 



Gen. 12. CyClOpS, Miiller, 1776 (ex parte). 



Generic Characters. Anterior division of body moderately tumid, and 

 generally more tapered behind than in front; lateral parts of the 3 anterior trunk- 

 segments well denned and sub-angular behind; last trunk-segment more or less 

 produced laterally. Tail slender and attenuated, with the genital segment in 

 female more or less dilated in front. Anterior antennae of varying length, and 

 more generally composed of 17 well defined joints, though in some cases, by 

 concrescence, their number may be considerably reduced ; those in male strongly 

 hinged, with the terminal section distinctly biarticulate. Posterior antennae with 

 all 4 joints well defined, the 1st carrying at the end posteriorly a long ciliated 

 seta. Rudimentary palp of the mandibles carrying 2 very long and densely 

 plumose setae accompanied by a short bristle. Maxillary palp scarcely extending 

 beyond the masticatory lobe, and provided outside near the base with 4 ciliated 

 setre, 3 of which issue from a slight expansion of the margin. Anterior maxilli- 



