History of British animals - University of Guam Marine Laboratory

40G MOLLUSCA. TRIGONIAD^E. Pinna2. A. echinata.— Obovate, gibbose, many muricated radii Upon the deepestvalve; flatter valve smooth, with the anterior ear pointed.— Sower. Min.Conch, t. ccxliii.— In the Inferior Oolite.3. A. costata.— Deep valve gibbose, transversely obovate, with eight smoothcostse ; ears nearly equal ; shallow valve nearly flat, with many radii ;anteriorear large, produced,? posterior ear small—Sower. Min. Conch, t. ccxliv.f. 1.— Upper Oolite.4. A. incequivalvis — Oblique, elliptical, convex, with a large projecting ear,covered with radiating striae, and many thin costse ; flatter valve convex.smooth, marked with diverging sulci, included within the deepest valve.Sower. Min. Conch, t- ccxliv, f. 2.— Middle Oolite.5. A. ovala.— Transversely ovate, convex ; posterior side elongated, blunt ;hinge-line long, forming part of the posterior wing, which is most distant.—Sower. Min. Conch, t. Dxii. f. 2— Inferior Oolite.6. A. lanceolata— Transversely linear; lanceolate, compressed; posteriorwing large, obtuse angled ; anterior wing minute, pointed. A doubtful shell.Sower. Min. Conch, t. Dcxii. f. 1.—In Lias.Gen. CI I.PINNA.— Shell longitudinal, cuneiform, equivalve;pointed at the base ;open at the top ; ligament marginallinear, very long, and subinternal.413. P. ingcns.— Shell oval, triangular, with transversearched striae ;flat at top, and straightat the hinder side.Penn. Brit. Zool. iv. 1 15. Mont. Test. Brit. 180.—P. laevis, Don. Brit.Shells, t. clii—P. ingens and fragilis,Turt. Biv. Brit. 222. t. xxii. f. 1 .— In deep water on the southern, western, and northern shores.Length about a foot, breadth half a foot ;semi-transparent, horn-colour ;compressed at the broad end, from which it runs, in front, nearly with astraight edge, for two-thirds, and then slopes suddenly to the apex a few;obsolete longitudinal ridges towards the back, and scaly wrinkles towards thefront. It is, however, rather irregular in its markings and outline. Whenexamined by a lens, the surface is finely punctured, like the Avicula hirundo.—This species appears to have been first discovered, as British, by the lateDr Walker. Montagu found it gregarious in beds, left dry at very low tidesin Salcomb Bay.414. Y.JraglUs. — Shell triangular ; front margin rounded ;scalyribs about ;eighteen.Penn. Brit. Zool. iv. 114, t. lxix. f. 80.—P. muricata, Don. Brit. Shells,t. x.—P. pectinata,Mont. Test. Brit. 178. Turt. Biv. Brit. 223. t. xix.f. 1 Southern coasts.Length six inches, breadth two and a half; pellucid corneous ; ; the longitudinalribs run the whole length of the shell ;towards the middle, in front,the scaly striae run obliquely to the margin.415. P. muricata.— Triangular, with ten or twelve broadribs, and intermediate smaller ones at the wide end, beset withconcave prickles.Pnlt. Dorset. 30—Mont. Test. Brit. 183. t. v. f. 3— Turt. Biv. Brit. 224.— Dredged near Weymouth.