20 DKEDGING EEPORTS. 



broadly rounded. Carapace excavated with large cells, which 

 haye a somewhat concentric arrangement. Length one third of 

 a line. 



Allied to C. eonvexa, hut in that species the carapace is less 

 tumid, the anterior extremity is broader, and the posterior pro- 

 cess is not central but inferior ; the excavations are not so large, 

 though the species attains much greater dimensions than C. 

 guttata. The close resemblance which C. guttata bears to a peach- 

 stone in all respects is most striking. 



Dredged in 1864 off Holy Island, and also 10-15 miles off 

 Seaham, in about 40 fathoms. 



The genus Cythere is so extensive, and the recent and fossil 

 species, already described, are so numerous, that it has become a 

 matter of no small difficulty to find appropriate names, which 

 have not been already pre-occupied by British or foreign authors. 

 It will be seen in the previous descriptions that I have been 

 unfortunately compelled to re-name many of the species, having 

 found that the names which I had at first proposed were already 

 appropriated to some fossil forms by Bosquet, Beuss, and Speyer. 



Gehtjs. CYTHEREIS, Jones. 

 Cythereis Umicola, n. sp. PL VI, figs. 1-4. 



Oblong, short : greatest height at the commencement of the 

 antero-dorsal slope ; length to breadth as one and three quarters 

 to one ; sub-compressed. Ventral margin straight, dorsal having 

 a long anterior slope from the highest point ; and a gradual 

 downward inclination from the same point posteriorwards. Ante- 

 rior extremity wide, rounded ; posterior extremity rather nar- 

 rower and subtruncate. Carapace having a greatly elevated 

 longitudinal rib a little within the ventral margin, from the 

 anterior extremity of which about three smaller ribs or dona- 

 tions proceed divergingly to the front of the valve; there are 

 also two nodular humps placed side by side near the posterior 

 termination of the hinge margin. Length, about one fourth of a 

 line. 



Discovered on the Dogger Bank, about 100 miles east of 



