304 



MANUAL OF THE MOLLUSCA. 



Distr. 50 sp. Chiefly in tropical seas, on rocky bottoms and in 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. dorealis, Conrad, inhabits the sea of Ochotsk ; C. abyssicola, 

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



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



? VEKTICORDIA, Searles Wood, 1844. 



Syn. Hippagus, Philippi, not Lea. (Verticordia, a name of Venus.) 



Type, V. cardiiformis (Wood, in Sby. Min. Con.) PL XVII. fig. 26. 



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

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

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

 lique ; epidermis dark brown. 



Distr. 2 sp. China Sea (Adams). Medit. ? (Forbes.) 



Fossil, 2 sp. Miocene . Brit. Sicily. 



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



SECTION 6. SINU-PALLIALIA. 

 Respiratory siphons lony ; pallial line sinuated. 



FAMILY XIV. 



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 

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

 pointed ; branchiae 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 chevron-shaped lines. 

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

 The Venerida appeared first in the Oolitic period, and have attained their 

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

 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. PL XX. fig. 7. 



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

 crenulated; cardinal teeth 33; pallial sinus small, angular; ligamen 

 prominent ; lunule distinct. 



