ments following the curvature of the lower margin; covered with a yellowish olive transparent epidermis.

Inhabits the English coast.

Fig. 5. S. radiatus.

Shell oblong oval, straight, smooth, with an internal rib from the hinge to the base.

Lister Conch. tab. 422. fig. 266.

Specimen violet with four white rays, extremely thin and brittle, rib white, strong; hinge in both valves callous; teeth in both valves bifid.

Inhabits the East Indies.

PLATE V.

Fig. 1. HINGE of TELLINA radiata.

Fig. 2. TELLINA rugosa.

Shell ovate, with transverse undulated wrinkles; hinge with two lateral teeth; one primary tooth in the right valve and two in the left bifid.

Born. Mus. Cæs. tab. 2. fig. 3, 4.

Specimen white, yellowish towards the beaks,

smooth within.

Inhabits the Indian and American seas.

Fig. 3. T. planata.

Shell ovate, compressed, transversely substriate, smooth, margin acute.

Born. Mus. Cæs. tab. 2. fig. 9.

Specimen purplish red with paler concentric bands, and a tinge of yellow about the beaks; thin, pellucid.

Inhabits the English coast.

Fig. 4. T. cornea.

Shell orbicular, smooth, horn-colour, transversely striate.

Lister Conch. tab. 159. fig. 14.

Specimen within dirty white passing into cinereous; without blueish white, polished; transverse striæ unequally deep; covered with an olive brown epidermis, which is darker in transverse bands, one usually darker than the rest. Lateral teeth elongated, inserted; primary ones small.

Inhabits the British coast.

Fig. 5. HINGE of CARDIUM echinatum.

Fig. 6. CARDIUM edule.

Shell antiquated, with 20-30 rounded ribs, obsoletely imbricate.

Lister Conch. t. 333. f. 170. t. 334. f. 171. Specimen pale brown, cinereous towards the margin; a dark brown and tawny spot upon the internal cavity of the anterior slope.

This shell, which is the common cockle of the market, is found in great numbers on the British coast, buried in the sand at no great distance from the surface.

Fig. 7. C. cardissa.

Shell cordate, valves compressed, dentato-carinate; beaks approximate.

Lister Conch. tab. 313.

Specimen white; equivalve; ribs oblique ; beaks slightly crossing each other; cordate impression on the area well defined; anterior side nearly flat, posterior one convex except towards the margin. Inhabits the Indian Ocean.

PLATE VI.

Fig. 1. HINGE of MACTRA lutraria.

Fig. 2. MACTRA stultorum.

Shell subdiaphanous, smooth, obsoletely radiate, purplish within; area gibbous.

Lister Conch. tab. 251.

Specimen pale brown inclining to cinereous, with paler rays, finely striate transversely.

Inhabits the English coast

Fig. 3. HINGE of DONAX Scortum.

Fig. 4. DONAX denticulata.

Shell very obtuse on the anterior side; lips transversely wrinkled; margin denticulate; shell striate longitudinally.

Lister Conch. tab. 376. fig. 218, 219.

Specimen white with obsolete purple rays, area cordate; fore part strongly marked with decussate striæ.

Inhabits the European and American seas.

PLATE VII.

Fig. 1. HINGE of VENUS concentrica.

Fig. 2. VENUS Paphia.

Shell subcordate, with thickened transverse wrinkles which are attenuated towards the anterior slope, lips complicated.

Lister Conch. t. 279.

Specimen white with interrupted brown rays, spots, and lines; areola cordate, brown; transverse ribs broad and convex,

It has been considered a needless increase of sections to separate, as in Gmelin's edition of Linnæus's "Systema," those shells which are said to be muricate before, from those which are not so, possessing a general subcordate form. There is in fact but one muricated species, V. Dione ; V. Paphia is included in the same division, which has no more title to the distinction than many individuals decidedly "unarmed;" the margin of the area, as is evident in the figure, being wrinkled and not muricate.

Fig. 3. V. edentula.