GINGLYMACONCHA. VENERIDZ. 293 
of the shell; the hinge with two minute, simple teeth in each 
valve ; the lateral lamellee lamelliform, subcompressed. 
The animal is unknown to me. 
1. CoRDULA AMNICA. 
Shells concentrically suleated ; the sulci striolated. Length 
a quarter; height three-eighths of an inch. 
Tellina amnica, Gualt. Test. t. vu. f. c, c.; Chem. Conch. vi. 
t. xm. f. 134; Mill. Verm. 205. no. 389; Gmel. Syst. 
Nat. 3242; Maton, Trans. Linn. Soc. ii. t. xin. f. 37, 38, 
T.; Dill. Dese. Cat. 105; Turt. Conch. Dict. 
Tellina rivalis, Donov. Brit. Shells, t. |xiv. f. 2; Pult. Cat. 
Dorset. t. vil. f. 2, a. 
Cardium amnicum, Mont. Test. Brit. 86. 
Cyclas obliqua, Lam. Hist. Nat. des Anim. sans Vert. v. 559. 
Cyclas amnica, Flem. Edinb. Encycl. vii. 
This species is found very commonly in sandy or rocky 
rivers; generally buried in the sand. 
The hinge, the muscular impressions and the contour of the 
shell, assure me that the animal, though unknown to me, must 
be distinct from the other genera of this Stirps. 
STIRPS II. 
The shells generally closed, equally convex; the umbones 
nearly central, not prominent; most generally no lamella be- 
fore and behind the cardinal teeth. 
Genus 39. Psammosia, Lamarck. 
Shells transverse, elliptic or ovately-oblong, flattish ; the 
umbones slightly prominent ; the hinge with two teeth in the 
left, and one in the right valve. 
The animal is not known to me. 
This genus is situated between the genera Sanguinolaria, 
Psammotea and Tellina; all the species are beautifully tinted 
with vivid colours ; there are several species in the European, 
African and Asiatic seas. 
