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SECTION III._CONCHIFERA LAMELLIPEDA. 
Tuts Section is divided into Five Families, viz. Conchze, Cardiacea, Arcacea, 
Trigoniana, and Naiada. 
CONCHA. —7 Genera. 
Three cardinal teeth at least in one valve, with as many, or less, in the other; sometimes 
mith lateral teeth. 
Tue Conche are divided into Fluviatiles and Marine. 
CONCH FLUVIATILES. 
Cycras.—Shell ovate-globose, transverse, equivalve, the beaks tumid; cardinal teeth 
very small, sometimes scarcely perceptible; occasionally two in each valve, one of 
them plaited in two; sometimes only one plaited or lobed tooth in one valve, and 
two in the other: lateral teeth transversely elongated, compressed, lamellar. — 
Ligament external. 
Plate VI. Fig. 8. (a) C. cornea. (Tellina cornea.—Linn.) 
(b) Inside of ditto. 
Cyrena.—Shell rounded, triangular, turgid or ventricose, inequilateral, solid, covered 
with an epidermis; the beaks eroded ; hinge having three teeth in each valve; the 
lateral teeth are nearly always two in number; one of them often near the cardi- 
nal. Ligament external, inserted in the larger side. 
(a) Lateral teeth serrated or denticulated. 
Plate VI. Fig. 9. (a) C. fluminea. (Tellina fluminea.—Gmel.) 
(b) Lateral teeth entire. 
[I have not been able to procure a species belonging to this division, to make a drawing from. ] 
GaatTHEea*.—Shell equivalve, subtriangular, covered with a greenish epidermis: cardi- 
nal teeth sulcated; two in the right valve, approaching at their base; three in the 
other, the middle one advanced, and separate: lateral teeth distant. Ligament 
external, short, protruding, turgid; nymphz prominent. 
Plate VII. Fig. 1. (a) G. radiata. (Venus subviridis—Gmel.) [Mr. G. B. Sowerby’s Cabinet.] 
(b) Hinge of ditto. 
* Galathea having been appropriated to a genus of Crustacea, Bowdich has substituted Megadesma 
as a name for this genus. 
