WG MOLLUSCA. VENERIDiE. Cytheuea. 



519- C orbiculata. — Orbicular, compressed and cancellated ; 

 beaks small, with a minute cordiform impression in front. 



Venus orb. 3Iont. Test. Brit. Sup. 42. t. xxix. f. 7 — Cyprina orbiculata, 

 Turt. Biv. Brit. 138 — Dunbar, Mr Laskey. 

 Diameter fths of an inch ; white; margin plain; two approximating teeth, 

 and one transverse, and rather remote where the margin is angular. 



EXTINCT SPECIES. 



1. C. lentiformis Orbicular, depressed, with concentric, i-eflected, minute, 



imbricated ridges ; posterior slope depressed, terminated by an angle at the 

 margin. — Venus exoleta, Park. Org. Rem. iii. 189. V. lent. Sower. Min. 

 Conch, t. cciii — Crag. 



2. C. Scutellaria Mant. Geol. 263. t. xxv. f. 2 — Plastic Clay. 



Gen. CXXVIII. VENUS.— Shell suborbicular, inequilater- 

 al ; hinge with three diverging teeth in each valve, the mid- 

 dle one in the left valve strong and bifid. / 

 * Margin zcithin crenulated. 



520. V. verrucosa. — Shell tumid, heart-shaped, with numer- 

 ous concentric ridges, broken into tubercles by longitudinal 

 grooves at both extremities. 



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Pectunculus omnium, crassissimus. List. Conch, t. cclxxxiv — Concha 

 cinerea, Borl. Corn. 275. t. xxvii. f. 32.— V. ver. Linn. Syst. i. 1130.— 

 V. ervcina, Penn. Brit. Zool. iv. 94. t. liv. f. 48 — V. ver. Don. Brit- 

 Shells, t. xliv. iVfo;if. Test. Brit. 112. Turt. Biv. Brit. 140 — Eng- 

 lish and Irish shores. 

 Length two inches and a quarter, breadth a little more ; rufous ; strong ; 

 depression before the beaks heart-shaped, the posterior, or cartilage depres- 

 sion, distinctly displayed only on the left valve ; the ridges are sharp, reflect- 

 ed and striated, and, towards the beaks the furrows are striated longitudinal- 

 ly ; the margin crenulated within. 



521. V. cass'ma. — Shell slightly compressed and heart-shaped, 

 M'lth numerous concentric entire ridges. 



Linn. Syst- i. 1130 V. erycina worn, Peim. Brit. Zooi. iv. t. liv. f. 48. 



A V. lactea, Don. Brit. Shells, t. cxhx — V, cass. Mato^i and liac 



kett, Lin. Trans, viii. 79. t. ii. f. 1. Turt. Biv. Brit. 141. t. ix. f. 1 — 

 Various parts of the coast. 

 Diameter about two inches ; whitisli ; ridges irregular in size, cui-ving to- 

 wards the hinge ; left valve at the ligament depressed and striate ; margin 

 sometimes very obtuse — This species is distinguished from the preceiluig by 

 being less tumid, and by the ridges being entire. 



522. V. rcfexa. — Shell compressed, dorsal margin behind the 



iK^aks nearly straight ; concentric ridges rising into thin plates 



rctrally, where they are waved and deflected. 



Laskey, Wern. ]\Iem. i. 384. t. viii. f. 1. Mont. Test. Brit. Sup. 40. 

 Flem. Encyc. Edin. vii. 95. t. ccvi. f. 1. Turt. Biv. Brit. 142. t. x. f 1, 



2 Various parts of the coast from Devon to Zetland. 



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