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height scarcely exceeding half the length, dorsal margin with a slight indication 

 to an angle in the ocular region and gently sloping behind, ventral margin slightly 

 sinuated, anterior extremity obliquely rounded, posterior a little narrower and 

 obtusely blunted, with the lower corner not at all produced; seen dorsally, 

 broadly oval in outline, with the greatest width in the middle and exceeding 

 somewhat half ihe length, side-edges quite evenly curved, both extremities 

 obtusely pointed, the anterior narrower than the posterior. Surface of valves 

 evenly convex, but coarsely sculptured throughout with very conspicuous and 

 somewhat irregular pits defined by a network of thickened stripes, anterior 

 edges and lower part of posterior divided into densely set obtuse denticles and 

 fringed with scattered very fine hairs, posterior part of ventral margin distinctly 

 jagged. Anterior antennae with the terminal joint comparatively small, scarcely 

 attaining half the length of the preceding joint. Posterior antennae with the 

 apical claws short and stout, flagellum remarkably thickened in the middle. 



Male, as usual, having the shell comparatively more elongate than in 

 female, but otherwise of a very similar appearance. Copulative appendages 

 rather large, but resembling in shape those of H. concinna, the terminal part 

 being very poorly developed. 



Colour of shell yellowish brown. 



Length of adult female 0.96 mm. 



Remarks. In the general shape of the shell this form has a perplexing 

 similarity to some of the species of the genus Cytheridea, for 'instance the 

 above-described C. papillosa. It is however at once distinguished by the very 

 different sculpture of the valves, agreeing in this respect, as also in the struc- 

 ture of the several limbs perfectly with the other species of the present genus. 



Occurrence. The only place, where I have met with this distinct species, 

 is at Korshavn, south coast of Norway. Several specimens, both males and 

 females, were taken here, some years ago, in a depth of about 20 fathoms, 

 muddy bottom. 



Distribution. British Isles, Bay of Biskay, Mediterranean. 



Gen. 41. Cythereis, Jones, 1849. 



Generic Characters. Surface of shell more generally rather uneven, with 

 variously formed projections or spines, anterior and posterior edges always 

 strongly denticulated; sculpture less coarsely marked than in the preceding 

 genus, in some cases quite inconspicuous. Hinge with the closing teeth well 

 developed. Eyes, when present, very conspicuous and adjacent to pellucid 



