Shell transverse, equivalve, no flexuosity; apices curved inward, opposed to each other; two primary and two lateral teeth, the posterior one nearest to the hinge; muscular impression simple, valves sometimes convex, strongly ribbed transversely, striated longitudinally, margins serrated and closely interlocking. _C. fimbriata._ The fringed Corbis. Pl. 8, fig. 1. Species white, rather thick, oval, a little elongated, almost equilateral; the cardinal and the lateral teeth well marked; the muscular impression anterior, rounded. 7. Lucina. Twenty species. In the hinge and lateral teeth it much resembles the Tellina, but differs from it in never being flexuous. This genus is more easily characterized by the orbicular, compressed, general form of the shell, than by the dental system, which is sometimes entirely effaced. Shell compressed, regular, orbicular, sub-equilateral; summits small and pointed, inclined anteriorly; hinge similar, but variable; two divergent cardinal teeth, little marked, and sometimes entirely effaced; two remote lateral teeth, with a pit at the base, sometimes obsolete; posterior ligament more or less sunk; two widely-separated muscular impressions, of which the anterior is narrow and long. Lucina Jamaicensis. L. Pennsylvanica. L. edentula. L. mutabilis. L. radula. L. squamosa. L. lactea. L. undata. L. circinaria. L. columbella. L. concentrica. L. divaricata. L. carnaria. L. scabra. L. reticulata. L. sinuata. L. pecten. L. lutea. L. digitalis. L. globularis. _L. Jamaicensis._ The Jamaica Lucina. Pl. 8, fig. 8. Species lenticular, striated concentrically; the teeth of the hinge variable, and sometimes obsolete. _L. undata._ The waved Lucina. Orbicular, thin, convex, undulated with fine irregular striæ; exterior pale yellow, interior white; margin glossy and plain. 8. Donax. The Wedge Shell. Twenty-seven species. The singularity of form that gave rise to its common name renders it easily distinguished. It very much resembles a wedge, being very broad and thick at one extremity, and gradually tapering towards the other. They vary in colour, but the most general is purple radiated on a white ground, diverging from the beak to the margin; many have an orange tinge, and others a pink hue; the interior generally partakes of the colour of the exterior. There are not, perhaps, two species that have absolutely the same hinge.