The following are the Worms of the Order MOLLUSCA, which construct and inhabit calcareous shells, the objects of our present consideration. Doris, or (according to Poli) Lophyrus; Chiton. Ascidea; Pholas, Mya, Solen, Mytilus. The animals inhabiting the Anomia and Nautilus are either sui generis, or have hitherto been unsatisfactorily described. Before we proceed to the systematic arrangement and explanation of the Genera, it will be necessary to acquire some knowledge of Terminology, as without this their technical descriptions will be unintelligible. The terms expressive of the forms and characters of the Univalves are placed first in the following Catalogue, because they include many of those which apply equally to the Bivalves. THE NOMENCLATURE OF CONCHOLOGY. UNIVALVES. THE SEVERAL PARTS OF UNIVALVE SHELLS WITH THEIR SPECIFIC MARKS, FORMS, AND LATIN. DISTINCTIONS. ANFRACTUS. The WREATHS or WHORLS; the circumvolutions of the spire around the Columella, are either ancipites. Two-edged; longitudinally carinate at the sides, or bifidi. Bifid; divided transversely by a line or furrow, as it were, by a suture. canaliculati. Channelled; having a small excavated channel along the suture. carinati. Keeled; the whorls compressed angu larly. contigui. Contiguous; growing together. coronati. Crowned; surrounded towards the apex with a simple row of protuberances or spines. distantes. Disjoined; perfectly separate at the sides. frondosi. Leafy; having the varices spreading into leaf-like or crested forms. imbricati. Imbricated; covered with scales laid partly one over the other like tiles. indivisi. Entire; opposed to bifid. lamellati. Lamellate; plated, surrounded transversely with membranaceous excrescences. lineati. Lined; engraven with lines, either raised or excavated; either longitudinal, extending from the apex to the base, transverse, following the course of the whorls, or striate, rendered rough by transverse striæ. "Lines" sometimes express the tracing only of the colour. obsoleti. Obsolete; having the suture obliterated. scrobiculati. Furrowed; covered with little fur rows or excavations. scripti. Lettered; marked with various characters resembling letters. sinistri. Left-handed, heterostrephous, turning round the pillar from right to left, instead of pursuing their usual, opposite, course. spinoso-radiati. Spinosely radiate; beset with spines in a circle, either concatenate, united at their bases, or setaceous, like bristles. striati. Striate; encompassed with very fine raised or excavated lines: punctate striæ are those which have elevated or impressed points placed along them; the points may be concatenate, strung like beads, or pertuse, deeply excavated. sulcati. Sulcated; marked with broader lines, either hollow, ridged, or elevated. APERTURA. APERTURE, mouth; the orifice, entrance, or opening of the shell. bimarginata. Bimarginate; having the lip with a double margin. |