History of British animals - University of Guam Marine Laboratory

404 MOLLUSCA. MYAD.E. Lutraria.4. M. sulangulata. —Rather depressed, smooth; wider than long; nearlyequilateral, oblong-ovate an ; angle from the beak to the retral margin ventralmargin slightly restricted.—Sower. Min. Conch, t. lxxvi. f. ; 3.—LondonClay.5. M. lata Ovate, depressed retral side acuminated and truncated,;slightly gaping.—Sower. Min. Conch, t. lxxxi—In Crag.6. M ? lilerata.— Transversely oval, subequilateral, convex, smooth, thin,with obtuse angularly bent ridges on the central part ; angles of the ridgesin a longitudinal direction.— Park. Org. Rem. iii. 196. t. xiii. f. 16.— Sower.Min. Conch, t. ccxxiv. f. 1 Inferior Oolite.7- M ? scripta.— Transversely oval, subequilateral, convex, smooth, thin,with oblique angularly bent ridges on the central part ; angles of the ridgesin an oblique direction.— Soiver. Min. Conch, t. ccxxiv Inferior Oolite.8. M angulifera— ? Transversely elliptical, elongated, gibbose, with oblongangularly bent ridges upon the surface, retral hall widest, gaping ; angles ofthe ridges acute, in an oblique direction—Sower. Min. Conch, t. ccxxiv. f. 6,7.— Oolite.9- M ? gregaria. — Obovate, convex, subdeltoid, smooth ; retrally producedand truncated.— Sower. Min. Conch, t. ccclxiii— Upperfresh water Formation,Isle of Wight.10. M. arenaria.— Sower. Min. Conch, t. ccclxiv. and t. Dxxxi. f. 2.—Nor.folk and Suffolk Crag.11. M. depressa Obovate, depressed, very slightly gaping ; anterior sideshortest beaks ; prominent incurved, hinge-line straight, depressed—Sower.Min. Conch, t. ccccxviii.—Middle Oolite. This is probably a Panopeea, as itis stated that the ligamentis external and short.12. M. gibbosa Obovate, transversely furrowed, gibbose beaks ; prominent,incurved ;anteal side very short ;retral side rather attenuated and gaping.Soiver. Min. Conch, t. ccccxix.— Middle Oolite.13. M. plicata.— Oblong, ventricose, straight, anterior side short, and trans-—versely plaited ; posterior gaping, truncated. Sower. Min. Conch, t. ccccxix.f. 3 Green Sand.14. M ? angustata Valves unequal ; transversely elongated, thin, antiquated,irregularly compressed ; extremities obtuse, gaping; lower edge ofthe lesser valve concave.— Sower. Min. Conch, t. Dxxxi.— Upper marine Formation,Isle of Wight.Gen. CXL.— LUTRARIA. — Equivalve, transverse, gaping.;hinge with a broad vertical plate for the cartilage, supportingone or two teeth on its anteal margin.580. L. vulgaris.— Nearly equilateral, and rounded at bothextremities.Concha longa, List. An. Ang. 170. Conch, t. xiv—Mactra lutraria,Linn. Syst.i. 1 126. Penn. Brit. Zool. iv. 92. t. Iii. £ 44. Mont. Test.Brit. 99.—Lutraria elliptica,Turt. Biv. Brit. 65—In sand about lowwatermark.Length 2\ inches, breadth 5 ; yellowish-white, with a thin close cuticle ;slightly striated concentrically by the layers of growth, with remote obsoleteridges.1