VENUS. 405 



of the glacial epoch, and in them have only been found in 

 their southernmost portions, in Ireland, where it was dis- 

 covered by Captain James, R.E., during the researches of 

 the Geological Survey. 



V. CASINA, Linneeus. 



Suborbicular, or subquadrate, either whitish, or with a few 

 roseate rays ; rough with numerous lamellae : hinder dorsal area 

 never lineated. 



Plate XXIV. figs. 1, 5, 6. 



Venus casina, Linn. Syst. Nat. p. 1 1 30. — Linn. Trans, vol. viii. p. 79, pi. 2, f. 

 1.— Mont. Test. Brit. Suppl. p. 47. — Turt. Conch. Diction, p. 

 232 ; Dithyra Brit. p. 141, pi, 9, f. 1.— Fleming, Brit. Anim. 

 p. 446. — Macgilliv. Moll. Aberd. p. 264. — Brit. Marine 

 Conch, p. 86.— Brown, 111. Conch. G. B. p. 90, pi. 36, f. 15.*— 

 Chemn. Conch. Cab. vol.vi. p. 306, pi. 29, f. 301, 302.— Dillw. 

 Recent Shells, vol. i. p. 165. — Lam. Anim. s. Vert. (ed. Desh.) 

 vol. vi. p. 340. — Index Testaceolog. pi. 7, f. 14. — Hanl. Re- 

 cent Shells, p. 111. — LcivEN, Ind. Moll. Sueciae, p. 39. 

 Peclimculus memhnmaceus, Da Costa, Brit. Conch, p. 193, pi. 13, f. 4 (on the left) 

 Venus rejlexa, (Var.) Mont. Test. Brit. Suppl. pp. 41, 168. — Mem. Wer- 

 ner. Soc. vol.i. pi. 8, f. 1 (badly). — Turt. Conch. Diction, p 

 233 ; Dithyra Brit. p. 142, pi. 10, f. 1, 2.— Flem. Brit, 

 Anim. p. 446. — Macgilliv. Moll. Aberd. p. 264. — Dillw 

 Recent Shells, vol.i. p. 168. — Hanl. Recent Shells, p. 110, 

 suppl. pi. 16, f. 10. 

 Ve7nis lactea, Donov. Brit. Shells, vol. v. pi. 149. — Linn. Trans, vol. viii. p. 79. 



— Mont. Test. Brit. Suppl. p. 46. 

 Vemis discina. Lam. Anim. s. Vert. (ed. Desh.) vol. vi. p. 338. — Brit. Marine 



Conch, p. 86. 

 Verius JRuslerucii (Young) Payraudeau, Moll. Cors. p. 52, pi. 1, f. 26, 27, 28. 

 Cytlierea reflexa, Couch, Cornish Fauna, pt. 2, p. 26. 



This handsome bivalve being liable to certain modifica- 

 tions of form and colouring, has been subdivided into two 

 species, casina and reflexa ; but as their distinctive features 

 so merge into each other that it is often impossible to de- 

 cide to which of them a specimen would belong, we have 

 regarded the latter as merely a variety of the earlier known 

 and more commonly diffused casina. 



