61 
11 . Diastyloides serrata, G. 0 . Sars. 
(PI. XLV.) 
Diastylis serrata , G. 0. Sars. Om den aberrante Iirebsdyrgruppe Cumacea, p. 44. 
Specific Characters. —Female. Body moderately slender, with the anterior 
division oval in form, and considerably vaulted dorsally. Carapace very large 
more than twice as long as the exposed part of the trunk, and evenly arcuate 
above, frontal lobe short and broad, ocular lobule almost obsolete, surface nearly 
smooth throughout, though, on a closer examination, the upper part of the 
branchial regions appears clothed with very small, anteriorly-curving denticles; 
pseudorostral projection greatly produced, horizontal, tip acuminate and slightly 
deflexed, subrostral corners obsolete, lower edges of carapace coarsely serrate 
throughout their whole length. Last pedigerous segment with the lateral parts 
scarcely produced behind, though terminating in an acute corner. Tail slender, 
with the segments quite simple. Superior antennte with the peduncle not reaching 
to the tip of the pseudorostral projection, its 1st joint somewhat shorter than 
the other 2 combined. First pair of legs scarcely longer than the carapace, 
basal joint not nearly attaining the length of the remaining part of the leg, and 
strongly spinous on the lower edge, penultimate joint longer than the antepenulti¬ 
mate, last joint comparatively short, not even attaining half the length of the 
penultimate one; 2nd pair with the basal joint produced at the end below to a 
strong spiniform projection, antepenultimate joint about the length of the last 2 
combined; 3rd and 4th pairs rather slender and having the basal joint coarsely 
denticulate behind. Uropoda with the rami nearly equal in length, and not much 
shorter than the stem, the inner one slender and attenuated, with the 1st joint 
almost twice as long as the other 2 combined, spinules of the inner edge about 
12 in number (9 on the 1st, 2 on the 2nd, and 1 on the last joint), apical 
spine slender and well defined at the base. Telson comparatively short, scarcely 
exceeding in length 1 / 3 of the uropoda, its proximal part rather thick, distal part 
but slightly tapered, and armed on each side with about 5 small spinules, apical 
spines rather large and pointing straight behind. Colour whitish with a faint 
yellowish tinge. Length 6 mm. 
Aclult male very slender, with the anterior division far less tumid than 
in the female, and but slightly vaulted above. Carapace perfectly smooth and 
less deep than in female, pseudorostral projection somewhat shorter and more 
horizontal. Last pedigerous segment with the lateral parts narrowly produced 
behind. Tail very slender and having the segments unarmed. Antennse and 
