History of British animals - University of Guam Marine Laboratory

452 MOLLUSCA. CYCLAD.E. Cyclas.542. V. virginea.— Transversely oblong, with numeroussmooth, flat, concentric ridges, with narrow intervening furrows.Tellina lata, List. Conch, t. ccclxxxv.—Venus virginea, Linn. Syst.i.1136 V. rhomboides, Penn. Brit. Zool. iv. 97, t. Iv—V. vir. Mont.Test. Brit. 128. Turt. Biv. Brit. 156, t. viii. f. 8—South coast ofEngland, and west coast of Scotland.Length 1 ^, breadth 2 inches ; white with reddish markings retral extremitymore or less obliquely truncated with an obsolete angle from the beak;to the outer edge ; margin of the shell, at the cartilage, tumid ; a lanceolatemark before the beaks ventral ; margin obtuse.543. V. sarniensis.— Transversely ovate, with smooth, regulartransverse striae.Tellina fasciata, List. Conch, t. cccciii.—Venus sarn. Turt. Biv. Brit.153, t. x. f. 8 Guernsey and Zetland.Length 2 inches, breadth a little more. It chiefly differs from the preceding,of which it may prove to be only a variety, in its more rounded andtumid form, the striae not increasing retrally, and in the indistinctness ofthe anal angle.EXTINCT SPECIES.1. V. larmnosa.— Sower. Min. Conch, t. Dlxxiii.CYCLAD^.Gen. CXXX. CYCLAS.— Orbicular, tumid, with two primaryteeth in each valve, and a remote transverse lateralone on each side : the primary teeth sometimes bifid ;generallyminute and obscure ;ovoviviparous.544. C. cornens.— Equilateral, finely streaked concentrically;no impressionin front of the beaks ;ligament indistinct externally.Musculus exiguus, List. An. Ang. 150, t. ii. f. 31—Tellina cornea, Linn.Syst. 1. 1120 Tellina rivalis, Mull. Verm. ii. 202—T. cornea, Penn.Brit. Zool. iv. 89, t. xlix. f. 36 Cardium corneum, Mont. Test. Brit.86.— Cyclas rivalis, Drap. Moll. 129, t. x. f. 4, 5. — Cyclas cornea, Lamark,Hist. v. 558. Turt. Biv, Brit. 249, t. xi. f. 14—In muddypools.Length T 4 uths, breadth T s c ths of an inch; cuticle yellowish or olive, oftendark, with a pale band ;the outline slightly obtuse ventrally and retrally ;irregularly furrowed by the stages of growth. There are three varieties ofthis species: 1. Compressed, nearly lenticular; 2. Gibbous at the beaks, butbecoming thin or compressed towards the etlgcs ; 3.Nearly globular. TheC. pusilla of authors seems to be the fry of this species.545. C. rivicola.— Equilateral, finelystreaked concentricallya distinct oval ;impression in front of the beaks, and another