History of British animals - University of Guam Marine Laboratory

Pectunculus. MOLLUSCA. ARCADE. 401EXTINCT SPECIES.1. P. decussatus Transversely obovate ; sides rather straight ; surfacecovered with numerous longitudinal striae ; hinge teeth 25 to 30 ; marginthick, plain.— Sower. Min. Conch, t. xxvii. f. 1.—London Clay.2. coslatus.— Orbicular, depressed, with 25 longitudinal sharp ridges, and afew transverse striae ; hinge of 14 teeth ; margin serrated within— {Area deietaof Brander. Sower. Min. Conch, t. xxvii. f. 2—London Clay.3. P. Plumslediensis.— Transversely obovate, slightly oblique, with longitudinalobscure furrows, and minute transverse striae ; margin serrated withinSower. Min. Conch, t. xxvii. f. 3—Plastic Clay.4. P. variabilis.— Obliquely suborbicular, rather convex, finely striatedlongitudinally, becoming smooth or sulcated by wear ; teeth of the hingeand lines upon the area of the ligament, numerous ; beaks short, nearly close.—Sower. Min. Conch, t. cccclxxi. f. 1—In Crag It is probable that this shellis merely the Pectunculus pilosus, found in modern marine diluvium, instead ofa species connected with the anterior epoch.5. P. brevirostris.— Transversely obovate, rather oblique, and inequilateral,convex, obscurely costated, concentrically striated ; hinge line ratherstraight beaks ; short, not oblique ; hinge teeth few.—Sower. Min. Conch.1. cccclxxii. f. 1—London Clay.C. P. scalaris Obovate, convex, longitudinally ribbed, ribs narrow, sharp,area of the ligament short, projecting at the extremities, with a triangularpit in its centre ; margin irregularly toothed. — Sower. Min. Conch, t. clxxii.f. 2.—London Clay.7. P. sublcevis— Transversely obovate, equilateral, rather gibbose, withmany slightly 'elevated ribs ; beaks short, nearly close ; sides smooth.—Sower.Min. Conch, t. cccclxxii. f. 2 In Green Sand.8. P. umbonatus.— Orbicular, gibbose, nearly equilateral, longitudinallystriated and obscurely costated ; beaks prominent, obliquely curved, a lobeon the anterior side—Cardium umbonatum, Sower. Min. Conch, t. clvi. f. 2,3, 4, and P. umb. ib. t. cccclxxii. f. 3.— In Green Sand.9. P. minimus Orbicular, convex, smooth ;hinge line straight, prominentat the extremities ; margin not toothed—Sower. Min. Conch, t. cccclxxii.f. 5—In Oolite.10. P. oblongus.— Transversely oblong, inequilateral, rather convex, smooth;sides obliquely truncated; margin not toothed.^-Swer. Min. Conch, t. cccclxxi.f. 6 In Oolite.Gen. C. NUCULA.— Shell inequilateral, beaks approximate ;hinge line bent in the middle, with a spoon-shaped projectingtooth at the angle, and numerous lateral sharppointedteeth ;ligament internal.*Margincrenulated.— 408. N. nucha. — Shell subtriangular;beak near the shortend with an oval impression beneath.Area nucleus, Linn. Syst.i. 1143. Penn. Brit. Zool. iv. 1)8. Mont, Test.Brit. 141—N. nucleus, Turt. Biv. Brit. 176, t. xiii. f. 4—Not uncommon.VOL. I.C C