452 MOLLUSCA. CYCLAD.E. Cyclas. 



542. V. virginea. — Transversely oblong, with numerous 

 smooth, flat, concentric ridges, with narrow intervening fur- 

 rows. 



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 of 

 England, and west coast of Scotland. 



Length 1 ^, breadth 2 inches ; white with reddish markings ; retral extre- 

 mity more or less obliquely truncated with an obsolete angle from the beak 

 to the outer edge ; margin of the shell, at the cartilage, tumid ; a lanceolate 

 mark before the beaks ; ventral margin obtuse. 



543. V. sarniensis. — Transversely ovate, with smooth, regu- 

 lar transverse 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 prece- 

 ding, of which it may prove to be only a variety, in its more rounded and 

 tumid form, the striae not increasing retrally, and in the indistinctness of 

 the anal angle. 



EXTINCT SPECIES. 



1. V. larmnosa. — Sower. Min. Conch, t. Dlxxiii. 



CYCLAD^. 



Gen. CXXX. CYCLAS.— Orbicular, tumid, with two pri- 

 mary teeth in each valve, and a remote transverse lateral 

 one on each side : the primary teeth sometimes bifid ; ge- 

 nerally minute and obscure ; ovoviviparous. 



544. C. cornens. — Equilateral, finely streaked concentrically ; 

 no impression in front of the beaks ; ligament indistinct exter- 

 nally. 



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, La- 

 mark, Hist. v. 558. Turt. Biv, Brit. 249, t. xi. f. 14 — In muddy 

 pools. 

 Length T 4 uths, breadth T s c ths of an inch; cuticle yellowish or olive, often 

 dark, with a pale band ; the outline slightly obtuse ventrally and retrally ; 

 irregularly furrowed by the stages of growth. There are three varieties of 

 this species: 1. Compressed, nearly lenticular; 2. Gibbous at the beaks, but 

 becoming thin or compressed towards the etlgcs ; 3. Nearly globular. The 

 C. pusilla of authors seems to be the fry of this species. 



545. C. rivicola. — Equilateral, finely streaked concentrical- 

 ly ; a distinct oval impression in front of the beaks, and another 



