George Brettingham Sowerby II

“ The genera enumerated in this family are Cardium, Cardita, Cypricardia, Hiatella, and Isocardia. 11. Arcacea (plates, fig. 131 to 138) . These are known by having a row of numerous small teeth on the cardinal hinge in each valve. The genera included are, Cucullæa, Arca, Pectunculus, Nucula. 12. Trigonacea (plates, fig. 139 and 140) . It is doubtful whether this family should remain distinct. As of the two genera placed in it, the first, Trigonia, is thought by some naturalists to have strong affinities with Nucula, in the family of Arcacea ”

“ Corbulacea (plates, fig. 89, 90) , inequivalve, with an internal ligament resembling the Mactracea, but differing in having one valve deeper than the other, although regular shells. This small family contains only the genera Corbula and Pandora. 7. Lithophagidæ (plates, fig. 91 to 97) , irregular, terebrating, living in holes of rocks. The genera are Saxicava, Petricola, and Venerirupis. 8. Nymphacea (plates, fig. 98 to 110) , ligament external, generally placed upon a prominent fulcrum, which passes from the inside to the outside of the hinge; valves generally gaping at the extremities. ”

“ The shells of this family are found in fresh water, wells, ditches, and ponds. They are of a light horny structure, and simple form. The genera Planorbis, Physa, and Lymnea are placed in this family by Lamarck. 3. Melaniana (plates, fig. 313 to 317) . These are also found in fresh water, principally in rivers; they are thicker than those of the last family; and the greater part of them have elevated spires composed of numerous whorls. This family contains the genera Melania, Melanopsis, Pirena. ”

“ First, the Sessile Cirripedes or those which being composed of several valves, joined to each other, side by side in a circle, are attached to each other, or to submarine bodies by the basal portion of their own substance, and form a hollow, irregular cone, with the aperture above closed by an operculum consisting of two or more valves. ”

“ The shells of this family are inequivalve, equilateral, and attached to marine bodies by a tendon passing through one of the valves. The animals have, near their mouth, two elongated, ciliated arms, which are spirally rolled when at rest. The following genera are enumerated by Lamarck, Orbicula, Terebratula, Lingula. ”

“ This family contains the genera Sanguinolaria, Psammobia, Psammotæa, Tellinides, Corbis, Lucina, Donax, Capsa, and Crassina. 9. Conchacea (plates, fig. 111 to 121) , regular, having several cardinal teeth and sometimes lateral teeth. The Conchacea constitute one of the most beautiful and numerous families of the class; they present equivalve shells, which are always regular, unattached, and in general closed, especially at the sides; they are always more or less inequilateral. ”

“ This class constitutes the tenth of invertebrated animals, and receives its name from the jointed and ciliated branchia which protrude between the opercular valves. They are Multivalve shells, and were all included in the single genus Lepas in the system of Linnæus, and are commonly known by the name "Barnacles." Lamarck has, however, divided them into two distinct orders. ”