452 
MOLLUSCA. CYCLAD^. 
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. laminosa.— Sower. Min. Conch, t. nlxxiii. 
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. corneus. — 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. Biit. 
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 /oths, breadth j^oths 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 edges ; 3. Nearly globular. The 
C. pusilla of authors seems to be the fry of this species. 
545. C. rimcola. — Equilateral, finely streaked concentrical- 
ly ; a distinct oval impression in front of the beaks, and another 
