48 



3. Diastylis rugosa, G. 0. Sars. 



(PI. XXXVII). 



Diastylis rugosa, G. 0. Sars. Om den aberrante Krebsdyrgruppe Cumacea og dens 



novdiske Arter, p. 41. 



Syn : Diastylis strigata, Norman (adult male). 



Specific Characters. Female. General form of body rather robust, some- 

 what resembling that of D. cornuta, the anterior division being sharply marked 

 off from the posterior, and oval in form, with the dorsal face highly arched. 

 Carapace comparatively large and deep, with the surface rather uneven, exhibiting 

 laterally several transverse plicae, some of which, however, are rather indistinct 

 and partly interrupted, dorsal face moreover armed with 2 pairs of well-marked 

 spiniform projections, the anterior pair occupying the very same place as the 

 horn-like processes found in D. cornuta, but not nearly so large, the posterior 

 pair being more approximate and occurring behind the frontal lobe on the most 

 prominent part of the branchial regions; pseudorostral projection of moderate 

 size, conically produced, horizontal; subrostral corners very slight. Exposed part 

 of trunk without any spinules, but, like the carapace, clothed with scattered hairs ; 

 last segment with the anterior edge minutely crenulate, lateral parts scarcely at 

 all produced behind. Tail a little shorter than the anterior division and without 

 spinules. Eye well developed and rather conspicuous. Superior antennae mode- 

 rately slender, with the peduncle projecting somewhat beyond the tip of the 

 pseudorostral prominence, its 1st joint shorter than the other 2 combined and 

 unarmed, first pair of legs of a similar structure to those in D. cornuta, but 

 having the basal joint scarcely at all spinous, and the last joint about half the 

 length of the penultimate one; 2nd pair with the antepenultimate joint about the 

 length of the last 2 combined; 3rd and 4th pairs without any spinules on the 

 basal joint. Uropoda moderately slender, outer ramus very narrow and somewhat 

 longer than the inner, the latter with about 12 spinules inside (6 on the 1st, 3 

 on each of the last 2 joints), apical spine of moderate size. Telson not reaching 

 as far as the stem of the uropoda, proximal part rather thick, distal part coni- 

 cally tapering, and armed on each side with about 9 spinules, apical spinules of 

 same appearance as the lateral ones. Colour greyish white. Length 8 mm. 



Adult male very similar, as to general appearance, to that of D. 

 cornuta, but of smaller size, and having 2 distinct transverse plicas on each side 

 of the carapace anteriorly, the longitudinal carinai being less prominent and quite 



