298 0. 0. SARS, - [n. S. IV 



It is, however, worthy of note hei-e, tliat the North Caspian Sea, to wliicli 

 part the investigations have as yet heen confined, is every wliere very shallow, 

 even the greatest deptli 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 Gumacca tlie great majority are true 

 deep-water forms, only a few genera, among them the genus Psendociima, 

 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. 0. Sars, 1SG4. 



nOm den aberrante Krebsdyrgnippe Cumacea og dens uordiske Arteru. Christiauia Vid. 

 Selsk. Forbandl. 18G4. 



Generic Characteristics. — Body of rather various form, now compara- 

 tively short and compact, now very slender. Integuments generally not very 

 strongly incrusted, and exliibiting a distinct squamous structure. Carapace 

 of middle size, with the branchial regions well defined, and the antero-lateral 

 corners more or less produced; pseudo-rosti'al projection of somewhat various 

 structure, now distinctly prominent, and having the lateral lobes contiguous 

 along the dorsal line, now forming two obtuse, juxtaposed lamellje 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 coruete, 

 the median one being, however, sometimes obsolete in female. Superior 

 antennae in female with the outer flagellum 3-articulate, the inner veiy small, 

 uniarticulate; those in male only diftering in the outer flagellum being 

 5-articulate, and the inner biarticulate. Inferior antennie in female veiy 

 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 (epipoditeofraaxillipeds) 

 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 



Melanges biologiiinus. T. XIII, p. liiS. 



