tapering distall} 7 , inferior edge with a slender spine beyond the middle. 

 Posterior gnathopoda with the propodos exceeding half the length of the 

 carpus, oblong oval in form. Anterior pereiopoda slender, with the propodal 

 joint very narrow and the dactylus much elongated. Posterior pereiopoda 

 rather unequal in length, the penultimate pair being by far the longest; 

 last pair considerably shorter than the antepenultimate one and having the 

 basal joint very large, rounded quadrangular in form, and much longer than 

 the remainder part of the leg. Last pair of uropoda with the inner ramus 

 much shorter than the outer, terminal joint of the latter nearly as long as 

 the basal one and spiniform. Telson gradually tapering distally and having 

 1 or 2 pairs of dorsal denticles, cleft very narrow and extending far beyond 

 the middle, outer apical denticle longer than the inner. Colour (according to 

 Boeck) whitish with a faint reddish tinge at the end of each segment and of 

 the joints of the antennae and legs. Length of adult female scarcely exceed- 

 ing 5 mm. 



Remarks. The present species is easily distinguished from the 

 two forms described by the author from the Norwegian North Atlantic 

 Expedition. The above mentioned third not yet described species, for which 

 I would propose the name of C. a f finis, differs from the type species, not 

 only by its much larger size, but also by the lateral corners of the cephalon 

 being not straight but slightly upturned at the tip, and by the posterior 

 projection of the last epimeral plates of the metasome being considerably nar- 

 rower and more produced. 



Occurrence. - I have met with this form only very sparingly in a 

 few localities off the West coast of Norway, as also off the coast ofNordland 

 and Finmark, in depths varying from 50 to 100 fathoms. Prof. Lilljeborg 

 found it at Molde, Boeck at Haugesund, and Mr. Schneider at Tromso. 



Distribution, Arctic Ocean: Spitsbergen (Goes), the Murman Coast 

 (Jarzynsky), the Kara Sea . (Hansen), the Siberian Polar Sea (Stuxberg) ; 

 Bohuslan (Loveii) ; East coast of North America (Packard). 



G-en. 25. AlibrotUS, Milne-Edwards, 1840. 

 Syn: Caesiums, Boeck, (ex parte). 



Body rather slender and compressed, with not very large coxal plates. 

 Both pairs of antenna unusually elongated, with the nagolhi very slender 

 and composed of numerous short articulations; those of the male but little 

 longer than in female and without distinct calceolw. Epistome not distinctly 



14 Crustacea. 



