6i BIVALVES — OSTREA. 



Division VL— Valves slightly striated, lower valve turning up at 

 its sides, and the cartilage of the hinge placed in a deep narrow groove. 



Scientific Isiame. Locality. Corhtnon Name. 



Spondyloidea • • • • Indian Ocean Spondyloid O. • • 



Ovalis • ' • Oval do • • 



Division VII. — Valves coarse and rugged, and not comprehended in 

 the former divisions. 



The O. edulis (common Oyster) is too well known 

 for its nutritious and palatable qualities to require 

 description; the old shells are often covered with 

 various adhesions, such as Anomise, Serpulse, Lepades, 

 Sertulariee, and other marine productions. The inte- 

 rior has generally a pearly appearance, and some speci-^- 

 mens have been found containing pearls. 



They are to be met with in most seas, occasional- 

 ly in clusters, affixed to rocks or other substances. 

 In some places they are considered so profitable a 

 branch of commerce, that they are frequently formed 

 into large layers or beds, many miles in extent, in which, 

 by proper attention to their increase and growth, 

 their multiplication becomes immense. 



The Roman historians assert that the tables of the 

 great were supplied with this delicacy from the coasts 

 of Britain. 



Scientific Name. Locality. Common Name. 



Denticulata Cape of Good Hope • • • . Toothed Oyster • . 



Edulis British and other Seas • • • Eatable ... do • 



