46 LUCINIDiE. 



L. BOREALis, Linnseus, 



Suborbicular ; with raised concentric stri93. 



Plate XXXV., fig. 5, and (Animal), Plate M. fig. 6. 



Venus borcalis, Linn. Syst. Nat. ed. 12, p. 1134 (from type). — DoNOV. Brit. 

 Shells, vol. iv. pi. 130. 



Teliina radida, Mont. Test. Brit. p. 68. — Linn. Trans, vol. viii. p. 54. — Turt 



Conch. Diction, p. 175 Wood, General Conch, p. IS 3, pi. 



42, f. 4, 5.— Index Testaceolog. pi. 4, f. 71. 



Lucina radulu. Lam. Anim. s. Vert. (ed. Desh.) vol. vi. p. 225. — Tukt. 

 Dithyra Brit. p. 116. — Flem. Brit. Anim. p. 441. — Mac- 

 GiLLiv. Moll. Aberd. p. 255. — Brit. Marine Conch, p. 73. — 

 Brown, Illust. Conch. G. B. p. 98, pi. 39, f. 8, 9.— Philippi, 

 Moll. Sicil. vol. L p. 35, pi. 3, f. 17, and vol. ii. p. 25. — 

 Gould, Invert. Massach. p. GQ. — Hanl. Recent Shells, p. 75. 

 „ alba, (Young) Turt. Dithyra Brit. p. 114, pi. 7, f. 6, 7. — Brit. 



Marine Conch, p. 72. 

 „ (miiquata, (Fossil) Sow. Min. Conch, pi. 557, f. 2. 



The substitution of the name horealis for the better 

 known appellation of radula, is the result of an investi- 

 gation of the Linnffian species, still preserved in the cabinet 

 of the illustrious naturalist of the north. The contour of 

 this thread-girt bivalve is very nearly orbicular, the length 

 of the shell scarcely exceeding the breadth in the slightest 

 degree. The valves, which are rather veutricose in the 

 middle, but raj)idly diminish in convexity towards the mar- 

 gin, and chiefly anteriorward, are of an uniform more or 

 less pure white, and are covered in the adult with a deli- 

 cate yellowish or ash-coloured epidermis. Acute mem- 

 branaceous striae, which are rather closely arranged in a 

 concentric direction, and are more or less equidistant, ren- 

 der the entire surface rough to the touch ; the interstitial 

 spaces are not decussated, and there is no other sculpture 

 or division of surface present, excepting an obscure shallow 

 sulcus along the ordinary site of an umbonal ridge. The 



