It is recommended to the young student in Conchology to compare carefully the following Specific Descriptions with the Plates to which they refer, at the same time turning to the Nomenclature for the exact signification of the terms. By repeating this exercise till the species adopted as examples of the different genera and sections be perfectly known, a solid foundation will be laid for a more extensive acquaintance with the numerous beautiful and interesting individuals which are all to be arranged under some one or other of these generic forms. Those who may wish to acquire an accurate knowledge of the Linnæan system with still greater certainty, will find much benefit in selecting for examination a good specimen of each shell here illustrated, and placing them in a cabinet in their proper order. A regular series upon this plan, consisting of more or less valuable shells, with references to the annexed drawings, may be procured from Mrs, Mawe, 149 Strand, in whose superb collection almost every instructive subject may be viewed, and from whose liberality and science much information will be derived, SPECIFIC DESCRIPTION. PLATE I. Explanatory of the parts of Univalve Shells. PLATE II. Explanatory of the parts of Bivalves and Multi valves. PLATE III. Fig. 1. CHITON squamosus, Shell 8-valved, semistriate; marginal membrane scaly. Born. Mus. Cæs. p. 5. t. 1. fig. 1, 2. Specimen olive without, blue green within. Middle valves divided on each side of the central ridge into two parts, consisting of a triangular compartment striated from the apex to the base, and another very finely marked in the longitudinal SPECIFIC direction of the shell; terminal valves lunulate and striate; the scales on the marginal skin in alternate black and white divisions. Inhabits New South Wales, the Indian and American seas. Fig. 2. LEPAS Tintinnabulum. Lister Conch. tab. 443. fig. 285. Specimen with six erect valves, reddish purple, rayed with white, striated longitudinally, deeply towards the base; intermediate spaces purplish white, depressed, finely striated transversely. Aperture triangular. Operculum of four valves, two larger. Inhabits Sumatra. Fig. 3. L. anatifera. Shell compressed, 5-valved, smooth, placed on a peduncle. Lister Conch. tab. 439. fig. 288.. Specimen white with a pearly lustre;-Peduncle coriaceous, red or brown, wrinkled towards the shell, paler and pellucid towards the base; valves finely striate. Two larger valves three-sided, curvilinear; two upper ones nearly triangular; connecting one curved, narrow, rounded on the back. Inhabits nearly all seas. The specimen from which the annexed drawing was made, being a dried one, the peduncle is not inflated, nor does it preserve its original colour, but the skin which adheres to the margin of the valves is of a reddish orange. Fig. 4. PHOLAS candida. Shell oblong, muricate on all sides with decussate striæ. Lister Conch. tab. 435. fig. 278. Specimen white, very thin, within smooth, and rather silvery, both ends rounded; tooth of the hinge long, thin, and curved; margin of the hinge turgid, and projecting with a sharp curved fold towards the anterior part. One accessory valve lanceolate. Inhabits the English coast. SPECIFIC PLATE IV. Fig. 1. HINGE of MYA truncata. Fig. 2. MYA truncata. Shell ovate, truncate on the posterior margin, tooth of the hinge projecting forwards and very blunt. Lister Conch. tab. 428. fig. 269. Specimen dirty white, clothed with a yellowish brown epidermis which extends beyond the truncate side; thick, convex, deeply marked with irregular, transverse striæ, gaping widely at the truncated end, very smooth within. Solitary broad tooth of the hinge connected with the opposite valve by an interior cartilage. Inhabits the English coast. Fig. 3. HINGE of SOLEN Vagina. Fig. 4. SOLEN Ensis. Shell linear, rather curved; hinge with two teeth in one valve, and one locking between them in the other. Lister Conch. tab. 411. fig. 257. |