34 



duced; upturned process not much elongated, simply spiniform, and sharply 

 defined at the base. Chief piece of the copulatory apparatus of a somewhat 

 similar shape to that in the male of P. orbicularis, but less elongated. 



Colour not yet ascertained. 



Length of adult female 0.53 mm., of male 0.48 mm. 



Remarks. The present species may be at once distinguished from either 

 of the 2 preceding ones by the far less tumid shell, and more particularly by 

 the very sharply marked areolation of the valves. Another rather conspicuous 

 difference is found in the frontal armature of the right valve. 



Occurrence.- Some few specimens of this form were picked up from 

 samples collected at Korshavn, south coast of Norway, and taken at moderate 

 depths. I have not met with this form in any other place on the Norwegian coast. 



4. Polycope clathrata, G. O. Sars, n. sp. 



(PI. XVI, fig. 2) 



Specific Characters. Female. Shell very similar in shape to that in the 

 preceding species, but of smaller size and somewhat less high in proportion 

 to the length. Surface of valves very coarsely sculptured, exhibitin gan exceed- 

 ingly dense reticulation, the meshes being much smaller and more crowded 

 than in the preceding species, ventral edges nearly in their whole length fringed 

 with delicate spinules; right valve armed in front with a similar dentiform 

 process to that found in P. areolata, though of somewhat larger size. Caudal 

 lamellae not much different in shape from those in that species. 



Male rather smaller than female, but resembling it very much both in its 

 general appearance and in the characteristic sculpture of the valves. Left caudal 

 lamella with the anterior corner blunted, and the 3 foremost claws (in the 

 specimen examined) wholly absent, upturned process rather slender and almost 

 straight, terminating in a somewhat tortuous point. Chief piece of the copuh 

 tory apparatus comparatively large and lamellarly dilated at the end. 



Colour not yet ascertained. 



Length of female 0.47 mm, of male 0.42 mm. 



Remarks. The present form is closely allied to the preceding speci< 

 but of rather smaller size, and moreover at once distinguished by te mud 

 denser reticulation of the valves. The transformed left caudal ramus of the 

 male and the chief piece of the copulatory apparatus also exhibit well marke( 

 differences from those parts in P. areolata. 



Occurrence. Two specimens only of this form have as yet come und< 

 my notice. The male specimen was obtained from the same sample in whicl 



