50 
length of the stem, inner ramus with the 1st joint scarcely longer than the 2nd, 
spinules of the inner edge about 7 in number (3 on each of the 2 first joints, 
and one on the last), apical spine rather strong, mucronate, forming the imme¬ 
diate continuation of the joint. Telson not extending as far as the stem of the 
uropoda, and of the usual narrow lagenifonn shape, distal part sublinear, and 
having on each side only 3 or 4 spinules, apical spinules somewhat larger than 
the lateral. Colour greyish 'white, with a faint olivaceous tinge. Length scarcely 
exceeding 6 mm. 
Adult male much more slender than the female, with the anterior division 
considerably narrowed behind. Carapace rather large and somewhat vaulted above, 
being only armed in front with 3 small denticles, one originating from the ocular 
lobule, the other 2 occurring on each side of the anterior part of the frontal 
lobe, lateral carinse sub-obsolete. Last pedigerous segment with the lateral parts 
acutely produced behind. Tail unarmed. Uropoda and telson much more elon¬ 
gated than in female, exhibiting, like the other appendages, the usual transfor¬ 
mation. Body whitish, semipellucid. Length amounting to 8 mm. 
Remarks .—This form was first described by Kroyer in the year 1841 as 
Cuma lueifera, the specific name apparently referring to the fact that by the 
discovery of ovigerous females of this form, the hitherto much disputed question 
about the true nature of the Cumacea as perfect animals, could be finally settled. 
This form is easily distinguishable from the other Norwegian species in both 
sexes by the form and armature of the carapace. The Diastylis borealis of Sp. 
Bate is unquestionably identical with Kroyer’s species. 
Occurrence. —This species occurs rather plentifully along the whole Nor¬ 
wegian coast, from the Christiania Fjord to Yadso, in moderate depths, varying 
from 20 to 50 fathoms, muddy bottom. In the Christiania Fjord it is one of 
the commonest Cumacea, occurring rather abundantly even in the innermost part 
of the Fjord, in the immediate vicinity of the town. Adult males are sometimes 
found in considerable numbers, but only at certain limited periods of the season. 
They are extremely agile, being in almost constant motion, whereas the females 
lead a much more sedentary existence on the bottom, burying themselves more 
or less deeply in the loose mud. 
Distribution .—Kattegat (Meinert), Heligoland (Ehrenbaum), British Isles 
(Sp. Bate), Atlantic coast of North America (Verrill). 
