History of British animals - University of Guam Marine Laboratory

376 MOLLUSCA. SESSILIA. Discinagin not waved ; hinge patulous, short. — Anomise striata, Urc, Ruth. 31 1.t. xiv. £ 13, 14—A. resupinatus, Marl. Derb. t. xlix. f. 13, 14 In CarboniferousLimestone.16. S. Martini.— Transversely oval, convex, decussatedly striated ;thelongitudinal strife close, equal, minute ; the transverse ones broad, prominent,remote ;beak incurved, pointed ;hinge patulous, short. — Anomitislineatis, Mart. Derb. t. xxxvi. f. 3.—In Carboniferous Limestone.17- S. Urii— Smooth, a mesial furrow in each valve, ending in front in astraight wave of the margin; imperforate valve nearly flat, with a straightgibbosity at the apex ; perforated short— valve with a gibbous lengthened incurvedbeak; hinge patulous, Ure, "Ruth. 313. t. xiv. £ 12.— CarboniferousLimestone.18. S. exaralus—Perforated valve with broad, smooth, flattened ribs, dividedby shallow narrow furrows ; beak gibbous, incurved, hinge very short.I have frequently found the perforated valve of this well marked species,but always mutilated, and without the other valve.— In Carboniferous Limestone,West Lothian.Gen. MAGAS.—" An unequilateral unequivalved bivalve ;one valve with an angular sinus along an incurved beak ;line of the hinge and back of the other valve straight, withtwo projectionsnear the middle. A partial longitudinalseptum, with appendages attached to the hinge within.ri—( Soroerby.)1. M. pumilus.— The beaked valve is hemispherical, smooth, with a circularedge, and small, incurved beak ; the other valve nearly flat, with a longtransverse straight beak.— Sou-er. Min. Conch, t. cxix—In Chalk.Gen. XCII.SESSILIA.DISCINA.— Shell convex, uppervalve with anentire subcentral apex, under valve with the apex prominentand pierced by an oblong fissure, for the passage ofthe ligament.369- D. ostrcoides.— Upper valve with fine longitudinal ribs,crossed by concentric wrinkles.—Lamark, Hist. pt. i. 23C. Orbicula Norvegica, G. B. Sowerby, Lin.Trans, xiii. 468. t. xxvi. f. 2.— Habitat uncertain.Length about ffcths, breadth 4T 5 ths of an inch ; brown, the lower valvewhite the ; margin is more or less waved ; the ribs, as they proceed from theapex, are slightly bent, the concentric wrinkles of growth are numerous andunequal, especially near the margin ; inside, under the apex, with two irregularcallous ridges under valve ;concentrically wrinkled, a disc round the