726 CLASS xir. 



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 BRODER. 



Comp. Proceedings of the Zool. Soc. of London, 1832, pp. 28, 29. 



Placuna BRUG. (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., BLAINV. Malac. PI. 60, fig. 3, 

 GUERIN Iconogr., Moll. PI. 27, fig. 7, Indian Sea; Placuna sella LAM., 

 CHEMN. Tab. 79, fig. 714, HOUTTUYN Nat. Hist. i. 15, PI. 119, &c. (under 

 the name of Ostrea ephippium), &c. 



Carolia CANTRAINE. 



Comp. Bulletin de PA cad. royale des Sc. de Bruxelles, v. 1838, pp. in 

 113- 



Ostrea L. (in part), BRUG. 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 POLI) with body compressed, foot none, 

 margins of mantle thick, furnished with a double row of short 

 fimbrise. 



Sp. Ostrea edulis L., BASTER Natuurk. Uitsp. I. pp. 7181 ; BLAINV. 

 Malacol. PI. 60, fig. i, POLI Testae, utr. Sicil. n. Tab. 29, fig. i, Cuv. It. 

 Ani., ed. ill, Moll. PI. 72, fig. i ; Oyster, (Ester, 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 BASTER loc. cit. CARBONNEL in Maga&in de Zool. par 

 GUERIN, 1845. 



Ostrea virginiana LIST., GMEL., LISTER Conch. Tab. 200, fig. 34, Tab. 

 201, fig. 35, Encycl. method., Vers. PI. 79, figs, i 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., RUMPH. Amb. Rariteitk. Tab. 

 47, fig. D, BLAINV. Malac. PI. 60, fig. 2, GUERIN Iconoyr., Moll. PI. 24, 

 % 7- 



There are many fossil species of this genus both in the secondary and 

 tertiary formations. Comp. LAMARCK Ann. du Mus. vni. pp. 159 166; 



