304 



MANUAL OP THE MOLLUSCA. 



Bistr. 50 sp. Chiefly in tropical seas, on rocky bottoms and ia shallow 

 water; the Venericardia on coarse sand and sandy mud. W. Indies, U. S. 

 W. Africa, Medit. Red Sea, India, China, Australia, New Zealand, Pacific, 

 W. America. C. borealis, Conrad, inhabits the sea of Ochotsk ; C. ahysslcola. 

 Hinds, ranges to 100 fms. ; C. squamosa, to 150 fms. 



Fossil, 1 00 sp. Trias — . U. S. Patagonia, Europe, S. India. 



? VETiTicoRDiA, Scarlcs Wood, 1844, 

 Syn. Hippagus, Philippi, not Lea. {Verticgrdia, a name of Venus.) 

 Type, V. cardiiformis (Wood, in Shy. Min. Con.) PI. XVII. fig. 26. 

 Shell sub-orbicular, with radiating ribs ; beaks sub-spiral ; margins den- 

 ticulated; interior brilliantly pearly ; right valve vsdth 1 prominent cardinal 

 tooth ; adductor scars 2, faint ; pallial line simple ; ligament internal, ob- 

 lique ; epidermis dark brown. 



Distr. 2 sp. China Sea (Adams). ]\tedit. ? (Forbes.) 



Fossil, 2 sp. Miocene — . Brit. Sicily. 



Hiirpagus isocardioides. Lea, 1833, Eocene, Alabama: is edentulous. 



SECTION b. SiNU-PALLIALIA. 



Respiratory siphons long ; pallial line sinuated. 



FAMILY XIV. Venerid^. 



Shell regular, closed, sub-orbicular or oblong ; ligament external ; hinge 

 with usually 3 diverging teeth in each valve ; muscular impressions oval, 

 polished; pallial line sinuated. 



Animal free, locomotive, rarely byssiferous or burrowing ; mantle with 

 a rather large anterior opening ; siphons unequal, united more or less ; foot 

 liuguiform, compressed, sometimes grooved; palpi moderate, triangular, 

 pointed ; branchiee large, sub-quadrate, united posteriorly. 



The shells of this tribe are remarkable for the elegance of their forms 

 and colours; they are frequently ornamented with chevi-on-shaped lines. 

 Their texture is very hard, all traces of structure being usually obliterated. 

 The Veneiidce appeared fii'st in the Oolitic period, and have attained their 

 greatest development at the present time ; they are found in all seas, but 

 most abundantly in the tropics. 



Venus, L. 



Syn. Merceneria, Antigone and Anomalocardia (flexuosa) Schum. Chione, 

 Megerle (not Scop,) Erycina (cardioides) Lam. 1818. 



Type, V. paphia, L. PI. XX. fig. 7. 



Shell thick, ovate, smooth, sulcated or cancellated; margins minutely 

 crenulated; cardinal teeth 3—3; pallial sinus small, angular; ligament 

 prominent ; lunule distinct. 



