75 



of Lilljeborg is unquestionably identical with Kroyer's genus. The chief distinguishing 

 character of this genus consists in the structure of the last pair of legs, the powerful 

 chela formed by the outer ramus of the right leg in the male being especially 

 very characteristic. We know at present about 13 species of this genus, occurring 

 in different parts of the Oceans. All these species are marine and pelagic in their 

 habits, sometimes occurring in great shoals close to the surface of the sea. Two of 

 the species belong to the fauna of Norway, and will be described below. 



30. Centropages typicus, Kroyer. 



(PI. XLIX, L, LI). 

 Centropages typicus, Kroyer. Nat. Tidsskr. New series, Vol. 2, p. 588, PI. VI, figs. 22 2<i. 



Syn : Ichtyophorba denticornis, Glaus. 



Specific Characters. Female. Anterior division of body somewhat depressed, 

 seen dorsally, oblong oval in form, greatest width considerably exceeding 1 / s of 

 the length, anterior extremity conspicuously contracted, posterior scarcely at all 

 attenuated. Cephalosome less distinctly separated laterally from the 1st pedigerous 

 segment, front projecting below into 2 rigid, detiexed spikes. Last segment of 

 metasome with the lateral parts considerably expanded, and projecting at the 

 outer corner into a strong spiniform projection pointing obliquely backwards, and 

 somewhat more extant on right than on left side. Urosome conspicuously asym- 

 metrical, and generally turned more or less to left side, genital segment scarcely 

 longer, and but slightly broader, than the succeeding segment, and carrying near 

 the hind edge 4 somewhat irregularly arranged slender spines, 2 subventral and 

 2 subdorsal, the latter distinctly denticulate ; middle segment with a slight knob- 

 like protuberance on the right side; last segment comparatively short. Caudal 

 rami about twice as long as they are broad, and slightly widening distally, being 

 somewhat divergent and finely ciliated inside; innermost but one of the apical 

 setse nearly twice as long as the others. Eye forming a very conspicuous bulging 

 below. Anterior antennae, when reflexed, reaching to about the tip of the caudal 

 rami, 1st, 2nd and 5th articulations each produced in front to a well-developed 

 dentiform projection. Outer ramus of last pair of legs with the unguiform pro- 

 jection of the middle joint very strong, equalling in length the terminal joint. 



Male somewhat more slender than female, and having the lateral expan- 

 sions of last pedigerous segment less divergent, and conspicuously asymmetrical, 

 the left one being much larger than the right. Urosome perfectly symmetrical 

 and rather slender, composed of 4 segments only. Caudal rami somewhat longer 

 than in female, with the outermost seta quite short and spiniform, without cilia. 



