60 



Distribution. Greenland (Kr0yer), Jan Mayen (Nonv. North Atl. Exp.). 

 the Kara Sea (Stuxberg), the Siberian Polar Sea (Stuxberg). 



Gen. 2. DiaStylOldeS, G. 0. Sars, n. 



Generic Characters. General appearance that of the genus Diastylis, the 

 anterior division being sharply marked off from the posterior and rather tumid, 

 at least in the female. Carapace large, with the pseudorostral projection strongly 

 prominent. Tail slender. Eye wanting. Superior antennse about as in Diastylis. 

 Inferior antennse in female with the last joint very small, tuberculiform, and 

 without the apical plumose seta, which is replaced by a few very small auditory 

 bristles; those in male fully attaining the length of the body. Mandibles rather 

 unlike those in Diastylis, the body forming, as in Leucon, a broad lateral ex- 

 pansion, and having at the base of the thick molar process a conical projection; 

 masticatory part comparatively short and stout, cutting teeth indistinct, spines of 

 the inner edge few in number. The other oral parts, as also the legs, about 

 as in Diastylis. Pleopoda of male less perfectly developed than in that genus, 

 1st pair with both rarni uniarticulate, 2nd pair with the rami confluent to a 

 single piece. Uropoda with the rami very slender, the inner one generally longer 

 than the outer, and scarcely mucroniform, apical spine well defined at the base. 

 Tel son less produced than in Diastylis, with the apical spinules much larger 

 than the lateral ones ; in male very much bent, forming above at the flexure 

 a projecting angle. 



Remarks. I have felt justified in establishing this new genus to comprise 

 2 Norwegian species formerly referred by me to the genus Diastylis, but differing 

 from it very pronouncedly in some characters of apparently generic value. The 

 structure of the mandibles especially is very unlike that in Diastylis, and much 

 more resembling that found in the family Leuconidce. Moreover, the inferior 

 antennse of the female are rather different, and the pleopoda of the male are 

 less fully developed. It is as yet scarcely possible to state with certainty, if 

 there are any species among the exotic Diastylidse referable to this genus, though 

 it may probably be the case. 



