The Conchologist's First Book / A System of Testaceous Malacology, Arranged Expressly for the Use of Schools, in Which the Animals, According to Cuvier, Are Given With the Shells, a Great Number of New Species Added, and the Whole Brought Up, as Accurately as Possible, to the Present Condition of the Science.

by Edgar Allan Poe; Thomas Brown

Shell. Orbicular, the upper valve gibbous and conical; lower valve, flat, with three perforations. Inhabits the Indian Ocean. One species.

• Crania orbicula.

FAMILY XX.
Brachiopoda. Three genera.

1. Genus Orbicula. Pl. [IX].

Animal. Body much compressed and rounded; mantle open throughout its whole circumference; two ciliated tentacular appendages.

Shell. Orbicular, much compressed, inequilateral, very inequivalve; inferior valve very thin, adhering, imperforated, the superior patelloid, with the summit more or less inclined towards the posterior side. Inhabits the Norwegian seas. One living species. Two fossil.

• Orbicula Norwegica.

2. Genus Terebratula. Pl. [IX].

Animal. Depressed, circular or oval, more or less elongated, with two, long, pectinated, labial tentacula.

Shell. Thin, inequivalve, regular, subtrigonal; one of the valves larger and more dilated than the other, which is sometimes operculiform; hinge condyloid, in a straight line, and formed by two oblique articular surfaces in one valve placed between corresponding projections in the other. Inhabits the sea at the Zetland Islands. Two species are found in America. Thirteen living species. Thirty-eight fossil.