Ill 



70. Parathalestris Clausi (Norman). 



(PL LXV & LXVI). 

 Thalestris Clausi, Norman, Brit. Assoc. Report 1868, p. 297. 



Specific Characters. Female. Body moderately slender and conspicuously 

 compressed, being rather strongly built, with the integuments highly chitinized. 

 Cephalic segment about the length of the 4 succeeding segments combined, epime- 

 ral parts only slightly arched; rostrum very short and blunt at the tip. Urosome 

 scarcely half as long as the anterior division, and without any distinct lateral 

 rows of spinules on the segments, genital segment about the length of the remaining 

 3 segments combined. Caudal rami quadrangular and but slightly divergent, 

 apical setse of moderate length. Anterior antennae comparatively short, 9-arti- 

 c ul ate, distal part about half the length of the proximal one. Posterior antennae 

 rather robust, with the distal joint considerably expanded at the end, spines of 

 the anterior edge very strong and distinctly denticulate. Posterior maxillipeds 

 powerfully developed, with the hand very broad, dactylus strong and curved. 1st 

 pair of legs comparatively strongly built, with the outer ramus a little shorter 

 than the inner but somewhat stouter, terminal joint lamellarly expanded and 

 having the 2 innermost claws very strong and, like the much smaller 3rd one, 

 finely pectinate on the concave edge; apical claws of inner ramus likewise dis- 

 tinctly pectinate and somewhat unequal, the inner one being the longer. Last 

 pair of legs rather broad, foliaceous, distal joint rounded oval in form, inner 

 expansion of proximal joint broadly triangular and extending as far as the distal 

 one, marginal setse of both joints comparatively short. 



Male somewhat smaller than female, and exhibiting the usual sexual dif- 

 ferences. Last pair of legs much smaller than in female, distal joint short and 

 broad, cordate, with the marginal setse more or less spiniform, inner expansion 

 of proximal joint scarcely extending beyond the middle of the distal one, and 

 carrying 3 marginal setse, the outermost shorter than the others and spiniform. 



Colour generally golden yellow. 



Length of adult female 1.05 mm. 



Remarks. This form, first described by Norman, is closely allied to P. 

 liarpacticoides of Glaus, but is of larger size, and on the whole of more robust build, 

 both as regards the body itself and its appendages. 



Occurrence. I have met with this form rather abundantly along the whole 

 Norwegian coast, from the Christiania Fjord to Vadso, in the littoral zone among 

 algse, and, like other littoral forms, it is not infrequently left in tidal pools. 



Distribution. British Isles (Brady), coast of France (Canu). 



