64 



Distribution. Skagerak and Kattegat (Meinert), British Isles (Norman), 

 Several Stations of the Porcupine Expedition, down to 1630 fathoms (Norman). 



Gen. 3. DlaStylOpSiS, Sidn. Smith, 1880. 



Generic Characters. General appearance resembling that of Diastylis. 

 Carapace, however, less tumid, and having the antero-lateral corners well marked ; 

 pseudorostral projection more or less produced. Third and 4th exposed segments 

 of trunk more or less completely consolidated, at least in the female. Tail 

 slender and very flexible. Eye wanting. Superior antennae comparatively strongly 

 built, with the 1st joint of the peduncle unusually short, 3rd rather large and 

 clothed with plumose setse. Inferior antenna? in female very small, in male 

 almost attaining the length of the body. Oral parts about as in Diastylis. 

 First pair of legs with the outer 3 joints very slender; 2nd pair comparatively 

 short; the 3 posterior pairs very robust and adapted for digging. Pleopoda of 

 male of a similar structure to that in Diastylis. Uropoda and telson likewise 

 of essentially the same structure as in that genus. 



Remarks. This genus was established in the year 1880 by Prof. Sidn. 

 Smith, to comprise a North American species, D. Dawsoni, and the Rev. T. R. 

 Stebbing has recently pointed out, that Kr0yer's Cuma resima ought to be re- 

 ferred to the same genus. It was chiefly founded upon the supposed unique 

 character, that the 3rd and 4th exposed segments of the trunk appeared wholly 

 consolidated. It is true that these segments are very firmly connected; but in 

 the Norwegian species at least, a well-marked suture may in reality be proved to 

 exist between them. There are, however, otherwise sufficient differences from 

 Diastylis to warrant the maintenance of this genus. The species recorded by 

 Dr. Bonnier from the Gulf of Gascogne as Diastylopsis (?) tumida scarcely belongs 

 to this genus, as. like Leptostylis, it has rudimentary exopodites to the 3rd and 

 4th pairs of legs. 



