33 



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 from the Kara Sea as (..'. arct'tca. 



5 Crustacea. 



