38 BIVALVES OSTREA, 



than the Scallops, and are usually very rugged unfinished 

 looking shells. The Hammer Oyster (Ostrea Malleus) is 

 perhaps the most remarkable of all this tribe, its form 

 resembling that of a long headed hammer, or more pro- 

 perly a pick-axe ; there are two distinguishable varieties 

 of it, viz. the white and the black, both of which, when 

 in fine preservation, are considered rare and valuable. 

 These shells are rough and plaited on the outside, but 

 their inside is smooth and glossy, having a steel-blue co- 

 lor or metallic lustre diffused over the surface. 



The hinge of some of the species, as the Ostrea Perna 

 and Isognomon, have a perpendicular grooved line at- 

 tached to it. Some, again, as the Ostrea Vulsella, &c, 

 gape at the hinge; others terminate in a long beak from 

 the hinge upwards, as is the case in the Ostrea Cornucopias 

 (Horn of Plenty) and Virginica. Some species have all 

 the appearance ofa dried leaf, such as the Ostrea Folium, 

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

 trees, especially the Mangifera; they are also often found 

 affixed to the Gorgoniae. 



The common Oyster (Ostrea Eduljs) 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 

 Anomiae, Serpulae, Lepades, Sertulariae, and other ma- 

 rine productions. The interior of the shell has often a 

 pearly appearance, and some specimens have been found 

 which actually contained 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 



