'57 



Occurrence. Like the other known species of the present genus, 'this 

 form is exclusively an inhabitant of fresh water. The only locality where -I as 

 yet have met with it, is the lake Vansjo near Moss. It occurred here occasion- 

 ally, together with Moraria brevipes G. O. Sars, in a depth of 36 fathoms, 

 muddy bottom. 



Distribution. Bohemia (Mrazek), British Isles (Scott), Sweden (Lilljeborg). 



Gen. Ameira, Boeck. 

 46. Ameira dubia, G. O. Sars, n. sp. 



(PI. XXXVI). 



Specific Characters. Female. Body comparatively slender, with the 

 anterior division conspicuously dilated in its anterior part. Cephalic segment 

 large, equalling tri length the 3 succeeding segments combined, frontal edge 

 slightly angular, but without any distinctly defined rostrum. Urosome rather 

 narrow, equalling in length about Vj of the anterior division; genital segment 

 longer than the 2 succeeding segments combined; last segment fully as large 

 as the preceding one. Caudal rami short, being only slightly longer than they 

 are broad, and somewhat divergent; apical setae well developed. Anterior 

 antennae fully as long as the cephalic segment and distinctly 8-artieulate, ter- 

 minal part exceeding half the length of the proximale one. Posterior antennae 

 and oral parts of normal structure. 1st pair of legs imperfectly prehensile, the 

 inner ramus being only slightly longer than the outer, with the 1st joint scarcely 

 longer than the other 2 combined. The 3 succeeding pairs of legs of normal 

 appearance, except that the terminal joint of the outer ramus in the 3rd and 

 4th pairs has inside 3, instead of 2 setae. Last pair of legs with the distal 

 joint rather narrow, oblong in form, and somewhat constricted at the base, 

 marginal setae 6 in number; inner expansion of proximal joint comparatively 

 large, broadly linguiform, and extending beyond the middle of the distal joint; 

 marginal setae rather strong and 5 in number. 



Colour not yet ascertained. 



Length of adult female 0.90 mm. 



Remarks. This is a somewhat anomalous form, differing from the 

 more typical species of the present genus by the imperfectly prehensile cha- 

 racter of the 1st pair of legs and the greater number of setae on some of the 

 succeeding pairs. In these respects it agrees with the aberrant species, A. 

 simplex Scott, and should perhaps, together with this species, be included in a 



