149 



Remarks. This genus was established by Dana as early as the year 1846, 

 to comprise some species chiefly from the Pacific Ocean. The genus Dlas of 

 Prof. Lilljeborg is unquestionably identical with Dana's genus. It is easily re- 

 cognizable by the slender, pellucid body, and the very delicate and peculiar structure 

 of the several appendages. We know at present of a considerable number of 

 species from different tracts of the oceans, amounting to about 20 in all. Some 

 of them, however, may probably be referable to the nearly-related genus Para- 

 cartia of Scott. To the fauna of Norway belong 3 species, to be described below. 

 A 4th species, A. bifilosa Giesbrecht, will also in all probability be found to 

 occur off the Norwegian coast, as it has been observed both in the Baltic and 

 off the British coast. 



62. Acartia longiremis (Lilljeborg). 



(PL XCIX & C). 



Diets longiremis, Lilljeborg, De Crustaceis ex ordinibus tribus in Scania occurrentibus, 



p. 181, PI. XXIV. 



Specific Characters. Female. Anterior division of body, seen dorsally, 

 oblong fusiform in outline, greatest width about equalling 7 ? . of the length, an- 

 terior extremity somewhat contracted and obtusely truncated at the tip, posterior 

 gradually attenuated. Cephalosome attaining nearly half the length of the anterior 

 division, front without any trace of tentacular filaments below. Lateral lobes of 

 last segment of metasome rounded off at the tip, and each carrying dorsally a 

 rather conspicuous, delicate spinule. Urosome about equal in length to l / ?J of the 

 anterior division, genital segment fully as long as the other 2 combined, and, like 

 them, clothed both laterally and at the posterior edge with scattered, very delicate 

 spinules. Caudal rami sublinear in form, their length considerably exceeding that of 

 the anal segment, and slightly asymmetrical, right ramus projecting somewhat 

 beyond the left, and having the appendicular bristle nearer to the tip; marginal 

 setas densely plumose and somewhat divergent. Anterior antennse, when reflexed, 

 reaching about to the middle of the genital segment, none of the articulations 

 dentiferous. Length of apical spine of outer ramus in 2nd to 4th pairs of legs 

 considerably exceeding that of the whole ramus. Last pair of legs with the termi- 

 nal joint exserted to a slender setiform point, and somewhat curved in the middle. 



Male considerably smaller than female and easily recognizable by the 

 structure of the anterior antenna? and urosome. Caudal rami comparatively shorter 

 than in female, otherwise of a very similar appearance. Last pair of legs of 

 moderate size, 2nd and 3rd joints of right leg each expanded inside in to a rounded 



