PLICATULA.
OSTREA.
"Plicatula is a genus taken from Spondylus. Spondylus gæderopus, from the Mediterranean, is a common shell in collections.
"Podopsis is a fossil genus.
"Ostracea.
"The oysters and pectens differ so widely that they do not even rank in the same family.
"In the Ostracea are,
| Gryphæa | Ostrea. |
| Ostrea | The same. |
| Vulsella. | |
| Placuna | Anomia. |
| Anomia | The same—Antique lamp. |
"There is but one recent species of the first genus; but many fossil.
"The oyster is said to possess the most limited faculties of all shelly tribes. Immovable upon the rock or marine substance to which it is fastened, it receives no other nourishment than what the waves contribute, and indicates no other sign of life than opening and closing the valve of the shell. This genus still retains a great number of species: one section has the margin of the shell either simple, or waved, the other folded. O. edulis, common oyster, belongs to the first division.