BIVALVE SHELLS. 43 



with a perpendicular fLirrowed line, as in the species of the genus 

 Perna. The first family is again subdivided into three sections : 

 t valves equilateral, and ears equal ; jf ears imequal, and having one 

 of them generally cUiated with spires mthin ; ftt valves gibbous on 

 one side. 



Ostrea Icevis The Smooth Ostrea. Plate II. fig. 2. 



(Pecten Lcevis, Lamarck.) Shell thin, flat, suborbicular, 

 and pellucid, longitudinally and transversely striated; one 

 ear considerably larger than the other; colour various, some- 

 times orange, dark pink, &c. Not uncommon on the coast 

 of Northumberland. The striae on this shell are so minute, 

 that they can seldom be seen with the naked eye. 

 F Longitudinal and transverse strice, h n ears or auricles. 



Ostrea opercularis The Lid Ostrea. Plate VII. fig. 



14. Ears nearly equal; shell with about twenty rounded 

 ribs finely striated longitudinally and transversely ; beauti- 

 fully variegated with red, orange, purple, or brown ; upper 

 valve somewhat convex. Inside pure white. Three inches 

 long. Inhabits the British seas. 



The Ostreaj inhabit the ocean ; some lurk in the sand in large beds, 

 others adhere to rocks, and some to the mangrove trees which overhang 

 the sea on the shores of the "West Indies. 



The Edible Oysters of Britain are said to be superior to those of aU 

 other countries, and are common on naany of oiu* coasts. Indeed, this 

 country has been noted for oysters from the time of Juvenal, who flour- 

 ished in the beginning of the second century. In satirizing Montanus, 

 an epicure, he says : 



He, whether Circe's rock his oysters bore. 

 Or Lucrine lake, or distant Richborough's shore, 

 Knew at first taste. 

 The luxurious Romans were vei-y fond of oysters, and had their layers 

 or stews for them as we have at the present time. Sergius Orata was 

 the first inventor, as early as the time of L. Crassus the orator. He 

 did not make them for the sake of indulging his appetite, but through 

 avarice, and enjoyed great profits fi'om them. Orata got much credit 

 for his Lucrine oysters, for, says Pliny, the Bi'itish were not then 

 known. 



■ The oyster is a \erj entertaining object to tliose who are fond of 

 microscopic investigation. In the clear hquor around the animal, many 

 minute, round, h^iug animalcules have been found, whose bodies being 

 conjoined, form spherical figures with tails, not changing theii* place 

 otherwise than by sinking to the bottom, being heavier than the fluid ; 

 these have been fi-equently seen separating, and coming together again 



