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3. Gnathia elongata, Kniyer.
(PI. XXIII, fig. 1.)
Anceus elongatus, Kroyer, Nat. Tidsskr. Ny Rsekke, Bd. II, p. 388.
Specific Characters. Male: Body rather elongated,
with the mesosome
of nearly uniform breadth throughout, and the median constriction not very much
pronounced. Cephalosome of moderate size, rounded quadrangular, with the supra-
ocular processes well -defined. Dorsal face of both cephalosome and mesosome
very uneven, with irregular depressions, and clothed .-ill over with minute spinules
and short hairs. Penultimate pedigerous segment divided dorsally by a narrow
longitudinal groove into 2 halves. Metasome comparatively narrow, and scarcely
longer than the 2 posterior pedigerous segments combined, epimera small. Eyes
well-developed, though not very large. Mandibles comparatively small, with only
a very slight notch outside, inner edge obtusely produced in the middle, tip acute,
slightly incurved. Pereiopoda with small tubercles inside the outer joints. Ter-
I
minal segment of metasome considerably narrowed in its outer part, which is
conical in shape. Uropoda with the rami comparatively narrow. Female: Body
much broader than in male, with the last 3 pedigerous segments well-defined, and
together forming an oblong oval division about 3 times as long as that preceding it.
Cephalosome with the frontal part slightly produced and bidentate at the tip.
Pleopoda in both sexes with the rami quite smooth forming narrow site-like plates
not fitted for swimming, but apparently respiratory
in character. Colour of male
greyish white, with a light bluish tinge, of female, yellowish, seniipellucid, with
scattered brown dots. Length
in both sexes 4 mm.
Remarks. This form was first described by Kroyer from male specimens
collected off the Greenland coast, and was subsequently figured in (laimard's great
work. The female, however, has hitherto been unknown. Both sexes are easily
distinguishable from those of the other Norwegian species. The immature form
(Praniza), however, looks very like that of the 2 preceding species.
Occurrence. Along the whole Finmark coast, this arctic form is not infre-
guently met with. In the harbour of Hammerfest especially,
1 have taken it in
great abundance at a depth of from 20 to 40 fathoms, both sexes occurring in
nearly equal numbers, and in the same place, larva? (the Prani/a-form) were also
found rather plentifully. It extends southwards to the Lofoten Islands; farther
south, I have never met with it. The adult animal is very sluggish
structure of the pleopoda, indeed, showing it to be quite
larva?, on the other hand, move through the water with great agility,
probably, at times, lead a parasitic life on the skin of various fishes.
in habit, the
unable to swim. The
and most