103 



Gen. 27. ThaleStriS, Glaus, 1863. 



Generic Characters. Body robust, more or less curved ventrally, with 

 very thick and tough integuments. Cephalic segment large and somewhat com- 

 pressed in front, with the epimeral parts deflexed and more or less deep, in- 

 cluding between them most of the oral parts ; rostral projection short and thick, 

 deflexed, not detined at the base. Epimeral plates of the 3 succeeding segments 

 very thin and deflexed. Last segment of metasome not much narrower than the 

 the others, though with the epimeral plates less fully developed. Urosome in 

 female 4-articulate, with the genital segment more or less expanded and exhibiting 

 only slight traces of a subdivision; that of male distinctly 5-articulate. Caudal 

 rami with the apical setae, as a rule, very unequally developed. Eye large, in 

 some cases combined with lenticular thickenings of the integument. Anterior an- 

 tennae (in female) 9-articulate, 4th joint with the usual sensory filament. Posterior 

 antenna with the terminal joint rather coarse, and armed with strong claw-like 

 spines and geniculated setae; outer ramus comparatively small, biarticulate. Man- 

 dibles thickly incrusted, with the cutting edge coarsely dentate, palp well devel- 

 oped, biramous, with the basal part more or less expanded distally. Maxillae 

 with all parts well developed. Anterior maxillipeds short and compact, with a 

 strong claw at the outermost of the lateral lobes. Posterior maxillipeds very 

 powerful, hand more or less strongly dilated, terminal claw strong and curved. 

 First pair of legs with both rami 3-articulate and rather slender, subequal in 

 length, middle joint of outer ramus much elongated, last 2 joints of inner one 

 short, number of apical claws on the inner ramus 2, on the outer 2 or 3. Second 

 pair of legs with the middle joint of inner ramus carrying 2 natatory setae, in 

 male confluent with the last joint, and armed outside with one or 2 deflexed 

 spines. Last pair of legs in female generally very large, with both joints folia- 

 ceous, the proximal one forming a broad lamellar expansion inside. 



Remarks. This genus, established by Claus, is here taken in a much 

 more limited sense than has been done by that author and by most other carcinolo- 

 gists. In the restriction here adopted, it is chiefly characterised by the compara- 

 tively robust body (which generally exhibits a more or less pronounced ventral 

 curvature), the unusually thick and tough integuments, and the nature of the ros- 

 trum, which forms the immediate continuation of the cephalic shield, without 

 being defined from it by any suture or indentation at the base. There are 5 

 species belonging to the Norwegian fauna, which will be described below. 



