298 . G. 0. SARS, [N. sm 
It is, however, worthy of note here, that the North Caspian Sea, to which 
part the investigations have as yet been confined, is everywhere very shallow, 
even the greatest depth not exceeding 6 fathoms, and thus may be supposed 
to exhibit rather uniform physical and biological conditions. Now, it is well 
known, that of the hitherto known Cumacea the great majority are true 
deep-water forms, only a few genera, among them the genus Pseudocuma, 
being represented in quite shallow water. It therefore seems to me highly 
probable, that on a future investigation of the greater deeps of the Caspian 
Sea farther south, other Cumacean genera will also be found to be represented. 
Of the 10 species treated of below, only one has been previously de- 
scribed; all the others are new to science. The discovery of these additional 
species will necessitate a new improved diagnosis of the genus. 
Gen. Pseudocuma, G. Ο. Sars, 1864. 
«Om den aberrante Krebsdyrgruppe Cumacea og dens nordiske Arter». Christiania Vid. 
Selsk. Forhandl. 1864. 
Generic Characteristics. — Body of rather various form, now compara- 
tively short and compact, now very slender. Integuments generally not very 
strongly incrusted, and exhibiting a distinct squamous structure. Carapace 
of middle size, with the branchial regions well defined, and the antero-lateral 
corners more or less produced; pseudo-rostral projection of somewhat various 
structure, now distinctly prominent, and having the lateral lobes contiguous 
along the dorsal line, now forming two obtuse, juxtaposed lamella separated 
above by a deep incision. Exposed part of trunk consisting of 5 well defined 
segments, each provided with distinct laminar epimera. Metasome of the 
usual slender cylindrical form. Eye well developed, with generally 3 corneæ, 
the median one being, however, sometimes obsolete in female. Superior 
antennæ in female with the outer flagellum 3-articulate, the inner very small, 
uniarticulate; those in male only differing in the outer flagellum being 
5-articulate, and the inner biarticulate. Inferior antenne in female very 
small, forming a simple conical projection tipped with a single plumose seta; 
those in male well-developed and of the usual structure, with the peduncle geni- 
culate, and the flagellum filiform, consisting of very elongated articulations. 
Oral parts of normal structure. Branchial apparatus (epipodite of maxillipeds) 
with only a few sacciform gills. Posterior gnathopoda with the outer corner 
of the basal joint scarcely produced, and provided with only a single large 
plumose seta. The 2 anterior pairs of legs in female, and all but the last 
pair in male, provided with well developed natatory exopodites. First pair 
rather slender, with the terminal joint linear; 2nd pair having the ischial 
joint well defined, and exhibiting sometimes a very marked difference in the 
Mélanges biologiques. T. XIII, p. 462. 
