49 



Fam. Harpacticidae. 



Gen. Harpacticus, M. Edwards. 

 38. Harpacticus tenellus, G. O. Sars, n. sp. 



(PI. XXX). 



Specific Characters. Female. Body resembling in shape that of 

 H. gracilis Glaus, but of somewhat smaller size and more delicate structure, 

 with rather thin and pellucid integuments. Anterior division slightly depressed 

 and oblong oval in outline, being rather sharply marked off from the com- 

 paratively small urosome. Cephalic segment about the length of the trunk 

 and evenly contracted in front; rostral plate somewhat prominent and obtusely 

 rounded at the tip. Urosome not nearly attaining half the length of the 

 anterior division and much narrower; genital segment comparatively large, 

 occupying about half the length of the urosome. Caudal rami short, quadran- 

 gular, scarcely as long as they are broad; apical setae much elongated. An- 

 terior antennae very slender, attaining almost the length of the cephalic segment, 

 and composed of 9 joints, the 3rd and 4th of which are rather narrow and 

 elongated, subequal in size; terminal part, composed of the 5 outermost joints, 

 scarcely longer than the preceding (4th) joint. Posterior antennae resembling those 

 in H. gracilis, but of a more delicate structure. Posterior maxillipeds with the 

 basal part much elongated and narrowed distally, hand less dilated than in 

 the said species, being about twice as long as it is broacj and somewhat curved, 

 palmar edge well defined and armed, at some distance from the end, with a 

 very conspicuous spiniform process curving upwards along the edge. 1st pair 

 of legs built on the same type as in H. gracilis, but of more delicate structure, 

 with the rami comparatively narrower, the inner one about the length of the 

 1st joint of the outer. Natatory legs of the usual structure. Last pair of 

 legs with the distal joint oblong oval in form and comparatively narrower 

 than in H. gracilis; inner expansion of proximal joint less produced. Ovisac 

 large, rounded oval in form. 



Male fully as large as female and exhibiting the usual rather strongly 

 marked sexual differences. Anterior antennae conspicuously hinged, though far 

 less robust than in H. gracilis. Posterior maxillipeds scarcely more powerfull 

 than in female. 2nd and 3rd pairs of legs transformed in a much similar 

 manner to that in H. gracilis. Last pair of legs much reduced in size, with 

 the proximal joint very small and not at all expanded inside, 



7 Crustacea, 



