48 
3. Diastylis rugosa, G. 0. Sars. 
(PI. XXXVII). 
Diastylis rugosa, G. 0. Sars. Om den aberrante Krebsdyrgruppe Cumacea og dens 
nordiske Arter, p. 41. 
Syn: Diastylis strigata, Norman (adult, male). 
Specific Characters. — Female. General form of body rather robust, some¬ 
what resembling that of I), 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 lai’ge, 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 I), 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 plicae on each side 
of the carapace anteriorly, the longitudinal carinse being less prominent and quite 
