neiv Shells from the Falkland Islands. 113 



valve an oblique blunt keel ; umbones small, moderately 

 prominent; anterior side short, sharply rounded; posterior 

 side elongately produced, rounded above, angled below ; 

 dorsal margin straight ; ventral margin angularly rounded. 



Long. 3-75, lat. 7-25 mm. 



Hub. Falkland Islands. 



Malvinasia, gen. nov.* 



Shell small, inequilateral, subtrigonal ; right valve bearing 

 one small cardinal tooth and curved laterals on either side ; 

 left valve bearing a large, curved, club-shaped cardinal and 

 a broad, shell-like, posterior lateral tooth, the anterior lateral 

 in this valve being obsolete; ligament weak, internal. 



Malvinasia arthuri, sp. n. (Figs. 7, 8.) 



Shell subtrigonal, brownish yellow, polished, shining, 

 marked with rather coarse concentric growth-lines ; umbones 

 somewhat eroded, not prominent; dorsal margin sloping; 

 ventral margin rounded ; anterior side sloping above, 

 descending sharply below ; posterior side produced, rounded ; 

 cardinal tooth in right valve small, poitited; anterior lateral 

 tooth fine, curved; posterior lateral thickened above, curved, 

 tapering below ; cardinal tooth in left valve large, club- 

 shaped, curved in an anterior direction ; anterior lateral tootli 

 obsolete ; posterior lateral forming a broad, short, shelf-like 

 projection ; interior of shell whitish. 



Long. 2*5, lat. 3 mm. 



Hab. Falkland Islands. 



The genus outwardly has all the appearance of Nucida ; 

 the hinge-system, however, easily differentiates it from that 

 group. 



Davisia, gen. nov.f 



Shell small, slightly inequilateral, suborbicular ; right 

 valve bearing a slightly curved cardinal tooth, a weak ante- 

 rior lateral and a broadly expanded posterior lateral ; left 

 valve bearing an obsolete cardinal tooth, an expanded ante- 

 rior lateral, and a broad, straight, posterior lateral ; ligament 

 small, centrally situate. 



* " Malvinasia," from Malvinas, the Spanish name for the Falklands. 

 t " Davisia" named after the navigator Davis, who discovered the 

 Falkland Islands in 1592. 



Ann. & Mag. N. Hist. ISer. 8. Vol. v. 8 



