BIVALVES 0STRE4. 55 



the appearance of a dried leaf, such as theOstrea folium, 

 &c. &c. which often grows to the roots and stumps of 

 trees, especially the magnifera; they are also often found 

 affixed to the Gorgoniae. 



The common oyster (Ostrea edulis) is too well known 

 for its nutritious and palatable properties to require much 

 description ; suffice it to say, that the exterior of the 

 shell is usually covered with undulate and imbricate 

 scales, of a yellowish or pinkish olive cast, and the old 

 shells are often covered with various adhesions, such as 

 anomiap, serpulsp, lepades, sertulariae, and other marine 

 productions. The interior of the shell has generally a 

 pearly appearance, and specimens are often found con- 

 taining pearls. 



They are to be met with in most seas, affixed to rocks ; 

 and in some places are considered so profitable a branch 

 of traffic, that the greatest care is taken to promote their 

 generotion and growth. By proper management their 

 multiplication becomes immense. They are formed into 

 large layers or beds, extending many miles: these beds 

 generally, in favorable seasons, prove a submarine mine 

 of wealth to their proprietors. 



Almost all seas abound with Ostreae. The Ostrea di- 

 luviana is found fossil in the calcareous mountains of 

 Sweden. 



OSTREA. 



A. Valves furnished with ears^ and radiated — Scallop. 



a. equilateral: ears of the valves equal, 

 •Maxima. {Common Seal.) Striatula. 

 *idiCohdddi {Mediterranean S.) Minuta. 

 Ziczac. Plcuronectci {Compass S.) 



