450 MOLLUSCA. VENERIDiE. Vekus. 



2. V. plana. — Rather depressed, subcordate, slightly angular towards the 

 posterior side ; surface smooth ; edge entire Sower. Min. Conch, t. xx , low- 

 er figures — Green Sand. 



3. V. incrassata. — Orbicular, oblique, subdepressed, smooth ; posterior slope 

 straightish ; lunule large, obscure; edge entire; a conical tooth under the 

 lunule — Sower. Min. Conch, t. civ. f. 1, 2.— London Clay. 



4. V. gibbosa. — Orbicidar, gibbous, Avith many transverse rugae ; lunule 



large and short ; edge subcrenulated ; hinge rather large Sower. Min. Conch. 



t. civ. f. 3, 4 Crag. 



5. V. turgida. — Orbicular, gibbose, with concentric ridges ; valves thick, 

 with tumid crenulated edges — Sower. Min. Conch- t. cclvi. — Crag. 



6. "V. varicosa. — Subglobose, with projecting beaks, transversely furrowed, 

 two longitudinal varicose ridges within each valve. An obscure cast. — Sower. 

 Min. Conch, t. ccxcvi. f. 1, 2 Oolits. 



7« V. transversa Transversely ovate, elongated, gibbose ; nearly smooth ; 



anterior side small, rather pointed ; shell thin. — Sower. Min. Conch, t. ccccxxxii. 

 f. 1. — Londo7i Clay. 



8. V. rotundata Obovate, gibbose ; marked with numerous, minute, trans- 

 verse striae — {Brander, f. 91.) — F. lineolata, Smver. Min. Conch, t. ccccxxii. 

 f» 2. — Lo7idon Clay. 



9. V. elegans — Ovate, convex, transversely sulcated ; lunette ovate ; the 

 spaces between the sulci rounded and shining — ( V. gallina, Brander, f. 90.) 

 ■ — Sower. Min. Conch, t. ccccxxii. f. 3.— London Clay. 



10. Y . pectiuifera. — Transversely oblong ; carinated; surface longitudinally 

 sulcated, and supporting a few erect lamellae, commencing at the keel ; j)0S- 

 terior side smooth, truncated. — Soiver. Min. Conch, t. ccccxxii. f. 4. — London 

 Clay. 



11. V. ca-perala — Orbicular, rather depressed, covered with small, roiuided 

 concentric ridges; lunette cordiform, inconspicuous^ — Sower. Min. Conch, 

 t. Dxviii. f. 1. — Green Sand. 



12. V. parva, — Transversely obovate, rather convex, smooth ; lunette nar- 

 row — Soiver. Min. Conch, t. Dxviii. f. 4, 5, 6.— Green Sand. 



13. V. ovalis — Sower. Min. Conch, t. nlxvii. £ 12. 



14. V. Faba 3. 



1 5. V. Ringmeriensis — Suborbicular, with numerous, transverse concentric 

 striae, beaks incurved, approximate ; margin entire. A cast. — Mant. Geol. 

 126. t. xxv. f. 5 — Grey Chalk Marl. 



Mr Sowerby has described two shells connected with this group, under a 

 Genus which he terms Thetis, with the following character : " An equi- 

 valved, subequilateral bivalve ; more or less orbicular, and convex ; ligament 

 marginal ; three or four small acuminated teeth about the hinge ; the line 

 of attachment of the mantle ? has a deep sinus extending nearly to the beak ; 

 muscular impressions rounded, small, distant from the hinge." 



16. TJietis major. — Convex, orbicular ; posterior edge rather angular ; beaks 

 small. — Sower. Min. Conch, t. Dxiii. f. 1-4 Green Sand. 



l^. Thetis minor. — Gibbose, ^ider than long ; posterior edge rounded. Ve- 

 nus, No. 12 — Mant. Geol. Suss. Id.— Sower. Min. Conch, t. osiii. f. 6, 6.— 

 In Green Sand. 



