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segment of metasome, inner ramus rather thick, outer scarcely half as long, and
much narrower. Length 2.60 mm.
Remarks. - - As stated above, this form was first described by the present
author as a species of the genus Leptognathia. Having, however, subsequently
had an opportunity of examining the oral parts more closely, I have found it
necessary to separate it generically. It is easily distinguished from the other
Norwegian Tanaids by the strongly dilated metasome and the peculiarly rigid
appearance of the chelipeds.
Occurrence.. I have met with this form in a few places on the south
coast of Norway (Fredriksveern, Nevlunghavn, Mserdo) in comparatively shallow
water, the depth ranging from 6 to 20 fathoms.
Distribution. Mediterranean at Naples and Messina (the present author).
Gen. 6. CryptOCOpe, G. 0. Sars, 1880.
Generic Characters. Body more or less robust, with the cephalosome
considerably narrowed anteriorly, front truncated. Metasome scarcely broader
than the mesosome, and composed of 6 well-defined segments. Eyes wanting.
Superior antennae in female short, 4-articulate, in male much larger
and of a
structure similar to that in the genus Leptognathia. Mandibles well developed,
with the cutting edge coarsely dentated, and having on the right mandible a
rather large secondary lamella, molar expansion well defined, conic or lamellar.
Chelipeds rather strong and of a similar structure in the two sexes. Pereiopoda
slender, especially the 3 anterior pairs. Pleopoda in female very small and
rudimentary, with the rami extremely small, lobular; those in male well developed,
natatory. Uropoda in female short, biramose, rami very unequal; those in male
much more fully developed. Incubatory pouch formed only by 2 lamella issuing
from the bases of the 4th pair of pereiopoda.
Remarks. This genus is chiefly characterized by the rudimentary con-
dition of the pleopoda in the female. In the structure of the other appendages
it exhibits a close affinity to the genus Leptognathia', but the structure of the
mandibles is slightly different, and the incubatory pouch is constructed as in the
genus Tanais. Besides the Norwegian species described below,
the form at first
recorded by the present author as Tanais Voringii belongs to this genus. More-
over, Dr. Hansen has described a third species
5 Crustacea.
from the Kara Sea as (..'. arct'tca.