76 



Right anterior antenna with the middle section rather tumefied, its antepenultimate 

 joint having a strong denticle in the middle of the anterior edge. Chela of last 

 pair of legs very powerful, thumb strongly developed, of about the same length 

 as the dactylus, and unguiformly incurved at the tip. 



Colour. Body in both sexes rather pellucid, in female being often tinged 

 with orange or light chestnut in the middle of the anterior division. 



Length of adult female reaching 1.75 mm., of male 1.60 mm. 



Remarks. This handsome species was first described by Kro'yer under 

 the above name, and was subsequently recorded by Glaus, who regarded it as 

 new, and described it as Ichtyophorba denticornis. It is easily recognizable from 

 the 2nd Norwegian species by the strong rostral spikes, the form of the lateral 

 expansions of the last pedigerous segment, and that of the urosome in the female, 

 and finally, by the conspicuous dentiform projections on the anterior antennae, 

 and the very powerful chela of the right last leg in the male. 



Occurrence. This form is found along the whole southern and western 

 coast of Norway, at least up to the Trondhjem Fjord. On the other hand, I have 

 never met with it in any of the numerous samples of plankton from the northern 

 part of the Ocean examined by me, for which reason we are justified in regarding 

 it as a true Atlantic form. Off the Norwegian coast it occurs both in the open 

 sea and in the fjords, being often found in considerable abundance at the very 

 surface of the sea. It moves rather rapidly in the usual manner, now using 

 chiefly the posterior antenna, now darting about in an abrupt, jerking manner 

 by powerful strokes of the natatory legs and the urosome. 



Distribution. Off Cape Finisterre (Kro'yer), coast of France (Canu), 

 British Isles (Brady), Heligoland (Clans), Mediterranean (Giesbrecht), Atlantic 

 Ocean from Lat. 6 S to Lat. 62 N (Cleve). 



31. Centropages hamatus (Lilljeborg). 



(PL LII). 



Ichtyophorba hamata, Lilljeborg, De Crustaceis ex ordinibus tribus in Scania occurrentibus, 



p. 185, PI. XXI, PI. XXVL. figs 9-12. 



Syn: Ichtyophorba aut/uxfata, Glaus. 



Specific Characters. Female. Body comparatively more slender than in the 

 preceding species, with the anterior division, seen dorsally, somewhat attenuated 

 behind. Cephalosome well defined from the 1st pedigerous segment, front tipped 

 below with 2 soft recurved filaments. Last segment of metasome with the 

 lateral parts less expanded than in C. typicus, terminal spine shorter and 



