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SECTION III. — CONCHIFERA LAMELLIPEDA. 
This Section is divided into Five Families, viz. Conchae, Cardiacea, Arcacea, 
Trigoniana, and Naiada. 
CONCHAS 7 Genera. 
Three cardinal teeth at leant in one valve , with as many , or less, in the other; sometimes 
with lateral teeth. 
The Conchae are divided into Fluviatiles and Marina?. 
CONCHiE FLUVIATILES. 
Cyclas. — 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.) 
( h ) 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.] 
Galathea*. — 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; nymphas prominent. 
Plate VII. Fig. 1. («) G. radiata. (Venus subviridis. — Gmel.) [Mr. G. B. Sowerby’s Cabinet.] 
(6) Hinge of ditto. 
Galathea having been appropriated to a genus of Crustacea, Bowdich has substituted Megadesma 
as a name for this genus. 
