66 LUCINID^. 



D. ROTUNDATA, MoiltagU. 



Plate XXXV. fig. 6, and (Animal) Plate M. fig. 7. 



Tellina undafa, Pulteney, in Hutchins' Hist. Dorset, p. 30. 



„ rotundata, Mont. Test. Brit. p. 71, pi. 2, f. 3. — Linn. Trans, vol. viii. 

 p. 5Ci. — Dorset Catalog, p. 30, pi. 5, f. 8. — Turt. Conch. 

 Diction, p. 176. — Wood, General Conch, p. 187. — Dillw. 

 Recent Shells, vol. i. p. 99. — Index Testaceolog. pi. 4,f. 77. 

 Lucina rotundata, Turt. Dithyra Brit. p. 114, pi. 7, f. 3. — Brit. Marine Conch, 

 p. 73. —Brown, Illust. Conch. G. B. p. 98, pi. 40, f. 11.— 

 Hanl, Recent Shells, vol. i. p. 76, 

 „ lactea'? Desh. Encycl. Method. Vers, vol. ii. p. 374. 

 Psamniobia rotundata, Flem. Brit. Anira. p. 438. 

 Diplodonta dilatata, Philippi, MoU. Sicil. vol. i. p. 31, pi. 4, f. 7. 



„ rotundata, Philippi, Moll. Sicil. vol. ii. p. 24. 



Loripes „ Cuv. Regne Animal (ed. Croch.), pi. 103, f. 4. 



Venus fragilis, (Fossil), Nyst and West, Bull. Brux. vi. p. 401, pi. 3, f. 11. 



The shape is suborbicular, with a tendency to square- 

 ness, which latter is chiefly effected by the straightness and 

 ordinary absence of declination of the hinder dorsal margin. 

 The valves, which are decidedly inequilateral, moderately 

 capacious, and often ventricose, are rather more swollen 

 behind than in front, the chief swell being, however, sub- 

 central : they are rather glossy, not quite opaque, tolerably 

 firm in texture, and both externally and internally of an 

 uniform white. The surface, from being more or less dis- 

 tinctly marked with lines of growth, is not quite smooth, 

 but is perfectly free from striae, grooves, or lamellae, and is 

 not radiatingly subdivided (as in certain analogous shells), 

 by any marked elevation or depression of the lateral areas. 

 The anterior side, which is considerably the smaller, is 

 attenuated both above and below; its dorsal edge, which is 

 nearly rectilinear or subretuse near the beaks, and then 

 very slightly convex, sloping rapidly downwards, and form- 

 ing an obscure and almost central subangulation with the 



