12 



flagellum. Inferior antennae a little smaller than the superior, with the flagellum 

 3 4-articulate. Mandibles rather strong, with the molar expansion well-developed. 

 Palp of the anterior maxillae biarticulate and provided at the tip with several 

 slender setae. Epignath of the maxillipeds more fully developed than in most 

 other Tanaidae, forming a semilunar, ciliated plate terminating in a digitiform 

 lappet. Chelipeds very robust, especially in the male, hand in the latter much 

 larger than in female, and having the fingers subforcipate. Second pair of legs 

 slightly differing from the succeeding ones, the dactylus being very much elongated 

 and setiform; dactyli of the other pairs strongly hooked, and in the 3 posterior pairs 

 armed with comb-like teeth. Only 3 pairs of pleopoda present, all of them rather 

 fully developed, with densely setiferous lamelliform rami. Uropoda simple, not 

 much elongated, and composed of a limited number of articulations. Incubatory 

 pouch formed by 2 lamellae only, issuing from the base of the 5th pair of legs. 

 Remarks. - - This is the first recorded genus, and from it, therefore, the 

 whole family has been named. It is well distinguished from all the other genera, 

 especially by the structure of the metasonie and the limited number of pleo- 

 poda. The genus contains as yet 4 species, viz., T. tomentosus Kroyer, T. Caro- 

 lini M.-Edw., T. Dulonyi M.-Edw. and T. novw-zcalandice Thomson. Only the 

 first-named of these species occurs off the coasts of Norway. 



Tanais tomentosus, Kroyer. 



(PI. v.) 



Tanais tomentosus, Kroyer, Naturli. Tidsskr. Bel. IV, p. 183. 



Syn : Orossurus rittatns, Bathke. 

 Tanais vittatus, Lilljeborg. 

 Tanais liirticaudatus, Sp. Bate. 



Specific Characters. - - Body of female about 5 times as long as it is broad, 

 that of male somewhat shorter and thicker. Cephalosorne rather tumid in its 

 posterior part, and gradually narrowed anteriorly, frontal edge slightly angular in 

 the middle. Free segments of niesosonie defined by well-marked and rather deep 

 constrictions, the 3 posterior ones being somewhat longer than the 3 anterior, and 

 widening behind. Metasonie fully as broad as the niesosonie, but considerably 

 narrowed in its posterior part, the 3 anterior segments being much the largest, 

 and densely clothed laterally with stiff bristles, which on the 2 foremost ones are 

 continued across the dorsal face in band-like fringes; 4th segment very small, 

 terminal one scarcely broader, and subquadrangular in form. Eyes well developed, 

 with dark pigment and distinct visual elements. Superior antennae in female 



