176 VENERID. 
Venus, Linn. 
Syn.—Antigona, Schum., 1817. 
Distr.—1716 sp. World-wide. Low-water—140 fathoms. JV. 
astartoides, Behring’s Sea. V. verrucosa, Britain, Mediterranean, 
Senegal, Cape, Red Sea, Australia? Fossil, 200 sp. Oolite—; 
Patagonia, United States, Europe, India. V. verrucosa, Linn. 
(exiii, 7,8). V. puerpera, Linn. (exiil, 9). 
Shell thick, ovate, smooth, sulcated, or cancellated ; margins 
minutely crenulated ; cardinal teeth 3—3; pallial sinus small, 
angular; ligament prominent; lunule distinct. 
Animal with mantle-margins fringed; siphons unequal, more 
or less separate; branchial orifice sometimes doubly fringed, 
the outer pinnate; anal orifice with a simple fringe and tubular 
valve; foot tongue-shaped ; palpi small, lanceolate. 
MERCENARIA, Schum., 1817. (Crassivenus, Perkins, 1869.) 
Shell thick, ventricose, cordiform ; margins crenulated within ; 
three compressed, diverging teeth in each valve, the posterior 
of the right valve and anterior of the left valve strong and 
slightly bifid, the others lamellar; pallial sinus subtriangular. 
An American group, containing some of the largest and heaviest 
species of the genus. V. tridacnoides, a fossil of the United 
States, has massive valves, ribbed like the clam-shell. The North 
American Indians used to make coinage (wampum) of fragments 
of Venus mercenaria (exiii, 10-12) by perforating and stringing 
them on leather thongs; this is the edible hard-shell clam largely 
consumed on and near the coast of the United States. 
CRYPTOGRAMMA, Moreh, 1853. (Anomalocardia, Schum., 1817. 
Triquetra, Blainv.,1818.) Shell ventricose, triangular, prolonged, 
flexuous and attenuated posteriorly ; hinge with three cardinal 
teeth in each valve, the anterior one of the right valve small; 
margins crenulated. V.macrodon, Lam. (cxili,13). V. squamosa, 
Linn. (exiv, 30). 
CHIONE, Megerle, 1811. (Murcia, Rémer, 1867. Omphalo- 
clathrum, Klein.) Shell oval, triangular or subcordiform; margins 
finely crenulated ; hinge narrow, solid, with three teeth in the 
right valve and two in the left, the anterior tooth longest; liga- 
ment narrow; pallial sinus shallow. Mantle-margins folded and 
dentate; siphons short, unequal, the branchial doubly cirrated, 
the anal ciliated. V. gnidia, Brod. (exiil, 14). 
crrcUMPHALUS, Klein, 1753. Surface of the valves lamellar. 
V. plicata, Gmel. (cxiii, 15,16). 
TiMOCcLEA, Leach, Brown, 1827. (Leucoma, Rodmer, 1867.) 
Surface decussately striate. V. grata, Say. 
CHAMELMA, Klein, 1753. Surface concentrically striate. V. 
aphrodinoides, Reeve (exili, 17). 
VENTRICOLA, Rémer, 1867. Surface concentrically lamellate, 
V. rugosa, Chemn. 
S/ 
