726 CLASS XII. 
smaller, reddish-purple, and is found in the same seas. The species of 
Anomia are difficult to characterise, and are not yet sufficiently distin- 
guished. The fossil species occur especially in tertiary formations. 
Placunanomia BRopEr. 
Comp. Proceedings of the Zool. Soc. of London, 1832, pp. 28, 29. 
Placuna Brue. (Species of Anomia L.). Shell free, subequi- 
valve, flattened, thin, lamellose. Hinge interior, with two linear, 
divaricate crests, converging in the apex in one valve, received in 
two similar grooves in the other valve. Animal unknown. 
Sp. Placuna placenta, Anomia placenta L., Buainv. Malac. Pl. 60, fig. 3, 
Guiry Iconogr., Moll. Pl. 27, fig. 7, Indian Sea ;—Placuna sella LaM., 
Cuemn. Tab. 79, fig. 714, Hourruyn Nat. Hist. 1. 15, Pl. 119, &c. (under 
the name of Ostrea ephippium), &c. 
Carolia CANTRAINE. 
Comp. Bulletin de VAcad. royale des.Sc. de Bruxelles, v. 1838, pp. 111 
—II3. 
Ostrea L. (in part), Bruc. Shell adhering, inequivalve, lamel- 
lose, irregular, with left valve inferior, affixed, and right superior, 
plane, thinner. Hinge edentulous, a little cardinal pit receiving the 
ligament. Animal (Peloris Pout) with body compressed, foot none, 
margins of mantle thick, furnished with a double row of short 
fimbrie. 
Sp. Ostrea edulis L., Baster Natuurk. Uitsp. 1. pp. 71—81; BLAINV. 
Malacol. Pl. 60, fig. 1, Pott Testac. utr. Sicil. 1. Tab. 29, fig. 1, Cuv. R. 
Ani., éd. ill., Moll. Pl. 72, fig. 1; Oyster, Gster, Huitre, Auster; in the 
North Sea, Mediterranean, &c.; on the sea-banks at the Helder and on 
the Texel. This well-known species differs much in size and in the form of 
the shell, as will appear at once from a comparison of the figures cited. 
The oysters fished on the oyster-banks of Zealand become large in a shorter 
time than the English, and have flatter and less hard shells. Compare on 
Oyster-banks, besides BasreEr loc, cit. CARBONNEL in Magasin de Zool. par 
GUERIN, 1845. 
Ostrea virginiana List., GMEL., Lister Conch. Tab. 200, fig. 34, Tab. 
201, fig. 35, Encycl. méthod., Vers. Pl. 79, figs. 1—5; from the coast of 
N. America, differs by its greatly elongated form, and attains the remark- 
able length of 2 decimeters (nearly 8”).—By its margin folded in a singular 
manner at acute angles and its violet-red colour, is distinguished Ostrea 
crista galli CHEMN., Mytilus crista galli L., Rumpa. Amb. Rariteitk. Tab. 
47, fig. D, Buainv. Malac. Pl. 60, fig. 2, GuéRIN Iconogr., Moll. Pl. 24, 
fig. 7. 
There are many fossil species of this genus both in the secondary and 
tertiary formations. Comp. Lamarck Ann. du Mus. VIII. pp. 159—166 ; 
