width about half the length and the side-edges conspicuously angular, anterior 

 extremity bluntly truncated at the end, posterior sharply defined in front and 

 likewise bluntly truncated. Surface of shell rather uneven, each valve exhibiting 

 posteriorly, as in the 2 preceding species, an angular dorsal prominence and 

 a likewise somewhat angular subventral expansion, the anterior part being 

 moreover slightly umbonate laterally; edges smooth and rather densely hairy 

 at each extremity; sculpture well marked, of the usual kind. Antennae unu- 

 sually slender, terminal joint of the anterior ones exceeding half the length of 

 the preceding joint; flagellum of the posterior ones very short. 



Male a little smaller than female, with the shell comparatively narrower 

 and the dorsal margin more pronouncedly concaved in front. Copulative 

 appendages with the terminal part rather large and acutely produced in front; 

 basal part sending off below 2 unequal processes, the anterior one somewhat 

 spoon-shaped and curving forwards inside the terminal part, the other pointing 

 straight downwards and somewhat pyramidal in shape. 



Colour of shell light fuscous. 



Length of adult female 0.70 mm. 



Remarks. This form was recorded as early as the year 1863 by Speyer 

 from some fossil specimens found in tertiary deposits at Cassel, and was sub- 

 sequently observed by the present author in the living state, being described 

 under the name of Cythereis abyssicola. It is an easily recognisable species, 

 differing conspicuously from the other known forms in the shape of the shell. 



Occurrence. I have myself only met with this species in a single locality 

 of the Norwegian coast, viz., off the Lofoten islands, where it occurred in very 

 considerable depths, down to 300 fathoms. Norman has however found it 

 also in some places on the western coast. 



Distribution. British Isles, Dawis strait, Greenland, Spitsbergen. 



Fossil. Germany. 



91. Hemicythere concinna, (Jones). 



(PI. LXXXVII, fig. 1). 



Cy there concinna, .lones, Monogr. Tert. Entomostraca, p. 29, PI. IV, fig. 7 a f. 

 Syn: Cythereis clavata, G. O. Sars. 



Specific Characters. Female. Shell, seen laterally, pronouncedly clavate 

 in shape, much higher in front than behind, greatest height exceeding some- 

 what half the length, dorsal margin angularly bent in the ocular region and 

 sloping gradually behind, ventral margin almost quite straight, anterior extre- 



