26 



Occurrence. — Only 2 female specimens of this form have hithertho been 

 taken by ine. They were collected at Sauesund, west coast of Norway, from 

 depths of 50 to 100 fathoms. 



Gen. 4. LeptOgTiathia, G. 0. Sars, 1880. 



Generic Characters. — Body in female, as a rule, narrow and elongated, 

 subcylindrical, with the segments marked off by marked constrictions; that of 

 male much shorter and stouter. Cephalosome generally narrowed only in its 

 most anterior part, and having the front narrowly truncated. Metasome with all 

 its segments well defined, being much more fully developed in male than in female. 

 Eyes wholly absent. Superior antennas in female distinctly 4-articulate, 1st joint 

 the largest, in male much more fully developed, composed of a 3-articulate ped- 

 uncle and a well-defined, 4-articulate flagellum densely clothed with sensory fila- 

 ments. Mandibles very small and feeble in structure, cutting part narrow, molar 

 expansion forming a thin acuminate lappet armed at the tijj with a few small 

 denticles. Oral parts in male, excepting the maxillipeds, abortive, epistome form- 

 ing a rounded projecting lobe. Chelipeds in "female of normal appearance, with 

 the hand more or less expanded, thumb generally serrated inside; those in male 

 feebler in structure, with the hand narrower, and the fingers quite simple. 1st 

 pair of pereiopoda not very different from the 2 succeeding pairs, the 3 posterior 

 pairs generally more strongly built, and having the outer joints armed with spines. 

 Pleopoda in female rather small, sometimes wanting; those in male well-developed. 

 Uropoda, as a rule, biramous, sometimes, however, apparently simple, the outer 

 ramus not being distinctly defined from the basal part, rami always very unequal, 

 the inner one much the larger and Inarticulate, the outer with either one or 

 two articulations. Incubatory pouch normal. 



Remarks. — This genus is chiefly characterised by the feeble structure of 

 the mandibles. From the preceding genera it may moreover be at once distinguished 

 by the superior antenna? in the female being distinctly 4-articulate, not as in the 

 former 3-articulate. The genus comprises numerous species, which on the whole 

 are true deep-water forms and tubicolar in habits. Besides the 6 Norwegian 

 species described below, the arctic form Tanais gracilis Kroyer, as also Tanais 

 graciloides Lilljcborg, belongs to this genus. Moreover, the Paraianais rigidus 

 Sp. Bate and Leptochelia coeca Harger, ought to be referred to the same genus. 

 Finally, Mr. F. Bcddard has recorded a, species, L. australis, from the Challenger 

 Expedition. 



