History of British animals - University of Guam Marine Laboratory

Trigonia. MOLLUSCA. TRIGONIAD^. 40511. T. pennata Oblong, transverse, with concentric costae; along themiddle of the anterior side is a ridge from which many tuberculated ridgesdiverge each way.— Sower. Min. Conch, t. ccxxxvii. f. 6.—In Green Sand.1 2. T. elongata Elongated, gibbose, subtriangular ; anterior side obtuse,transversely costated ; posterior side separated from the anterior by a crenulatedcarina, bicarinated, longitudinally striated, striaegranulated— Sower.Mill. Conch, t. ccccxxxi— Upper Oolite.13. T. nodosa Obovate, depressed ; anterior part covered with rows oflarge knobs, a portion of the posterior part plain ; superior edge straight.—Sower. Min. Conch, t. Dvii. f. 1.—In Green Sand.14. T. imbricata.— Transversely oblong, depressed ; with five or six concentricdentated, subimbricated keels upon the rounded anterior side ; posteriorside obliquely truncated, ribbed— Sower. Min. Conch, t. Dvii. £ 2, 3.—Oolite.15. T. cuspidata Obovate, depressed, ribbed ; posterior side truncated,its lower angle pointed; ribs concentric, with projecting angles where theypass into the posterior side.—Sower. Min. Conch, t. Dvii.—Oolite.16. T. angulata.— Transversely elongated, convex ; posterior side produced,truncated, transversely striated, bounded by a crenulated line ; the remainderornamented with nodose ridges, bent at right angles as they pass over themiddle.— Sower. Min. Conch, t. Dviii. f. I.—Under Oolite.]7- T. pullus.-—Obovato-triangular, with transverse smooth ribs ; posteriorside obliquely truncated, marked with several crenulated ridges, and boundedby a strong crenulated keel ;lunette large, regularly striated across.—Soiver. Min. Conch, t. Dviii. f. 2, 3.—In Oolite.18. T. spectabilis.— Suborbicular, rather elongated, convex, nearly smooth,ornamented with about seven bent rows of large round tubercles upon theanterior side, and a few small ones scattered over the posterior side ; one rowof compressed tubercles upon the posterior slope—Sower. Min. Conch. t.Dxliv.—In Green Sand.Gen. CI. AVICULA.— Shell flat, oblique unequivalve, unequilateral;transversely produced in a straightline at thebase, where the sides are lobed, and the beaks rather remote; hinge linear, with a single tooth in each valve underthe beaks ;ligament linear external.— 412. A. hirundo. — With the tail as long as the wing.Turt. Biv. Brit. 220, t. xvi. f. 3—On the southern coasts of Englandand Ireland.Length 2 inches, breadth nearly the same ; smooth, or slightly scaly withthe layers of growth, but, under a lens, it appears finely punctured colour;green or brown ; inside pearly. It was first observed, as a native, by MissHutchins, in Bantry Bay ; and announced as British by Mr Sowerby in hisMin. Conch, i. 14.EXTINCT SPECIES.1. A. media.— Ovate, depressed ; wings large unequal, one wing acute,valves nearly equal ; length of the shell and hinge nearly equal ; surfacesmooth—Soim-. Min. Conch, t. ii.—London Clay.