308 



distally, 1st joint much the largest and very thick, 3rd joint shorter than 2nd, 

 terminal part about half the length of the proximal one, with its 1st joint very 

 small. Posterior antennae with the terminal joint shorter than the proximal one 

 and spatulate in form, being armed at the tip with 4 strong, claw-like spines; 

 outer ramus somewhat lamellar and carrying on the tip 4 subequal setae. Mandibular 

 palp comparatively large, with 4 coarse plumose setae. Anterior maxillipeds with 

 the digitiform lobes rather short and thick. Posterior maxillipeds of moderate 

 size, hand narrow oblong in form and densely ciliated inside, dactylus armed at 

 the inner edge with a row of slender spinules. Natatory legs coarsely spinulose, 

 with the setae much reduced; spines of outer ramus however very coarse. Last 

 pair of legs with the distal joint well defined and short spatulate in form, car- 

 rying 5 marginal setae, 2 of which are very thin, the other 3 strong and densely 

 plumose; proximal joint with a transverse row of 4 coarse spinules at the junction 

 with the distal joint, its inner expansion not at all produced, the hind edge being 

 almost straight and provided with 4 coarse plumose setae. Ovisac of moderate 

 size, rounded oval in form. 



Colour reddish brown. 



Length of adult female 0.70 mm. 



Remarks. The above-described form is undoubtedly identical with that 

 recorded by Lilljeborg as llyophilus fiexibilis. This author considered it to 

 be both specifically and generically different from Nannopus palustris of Brady, 

 and I was at first of the same opinion myself. Seing however that Dr. Canu, 

 in his work on the Copepoda of Boulonnais, has described the very same form 

 under the name of Nannopus palustris Brady, I have again carefully compared 

 the imperfect description and figures given in Brady's Monograph, and have 

 thereby been induced to believe that in all probability the identification of 

 the species by Dr. Canu will prove to be correct. The habitus-figure given by 

 Brady (dorsal view of the animal) has apparently been made from a mounted 

 specimen in which, by the pressure of the cover-glass, the form of the body has 

 been somewhat injured. The 2 detail-figures (a leg of the 1st and 4th 1 ) pairs) 

 do not, on the other hand, exhibit any essential difference from the structure 

 found in the present form. 



Occurrence. I have only met with this form in a single locality near 

 Christiania. It occurred there occasionally in a shallow creek of the Fjord, on 

 a muddy bottom close to the shore. As observed by Prof. Lilljeborg, the 

 movements of the animal are very slow, and it seems to be quite devoid of 



J ) Not the 3rd pair, as indicated both in the text and in the explanation of the plate. 



