CHIONE. 421 



cordiforrn ; margins of the valves finely crenulated. Hinge 

 narrow, solid, tri-dentate in the right valve, bi-dentate in 

 the left ; teeth divaricate, unequal, the anterior tooth the 

 longest ; ligament narrow, external. Pallial line with the 

 sinus nearly obsolete, or very short and triangular. 



Ex. C. fasciata, Da Costa, pi. 107, fig. 5. Shell, C. 

 Gnidia, Broderip and Sowerby, 5, a, 5, b. 



In this genus the animal is ovately triangular ; the anal 

 siphon is furnished with a conical valve ; the gills are broad, 

 unequal, sub -quadrangular, widely plicate, and united pos- 

 teriorly ; the labial palps are small and triangular ; and the 

 foot is compressed and trigonal. The surface of the shell, 

 which varies in form, is lamellar, cancellated, smooth, or 

 transversely striated; there are no anterior lateral teeth, 

 and the primary teeth are triangular. The species of 

 Chione are numerous, and are widely distributed, being met 

 with in the seas of most tropical and temperate countries. 



Species of Chione. 



Amathusia, Phil. imbricata, Sow. 



caelata, Mice. lima, Sow. 



Californieusis, Broil. marica, Linn. 



callosa, Conr. neglecta, Sow. 



caucellata, Gronov. Nuttallii, Conr. 



Cochinensis, Sow. ornatissima, Brocl. 



Columbiensis, Sow. ovata, Pcnn. 



compta, Sow. pygmaea, Lam. 



costata, Quoy and Gaim. ruderata, Desh. 



coste\\ifeYa,Adams and Reeve. scabra, Wood. 



crenifera, Sow. simillirna, Sow. 



decorata, Brod. and Sow. striatissima, Sow. 



fluctifraga, Sow. Stutcbburyi, Gray. 



Gnidia, Brod. and Sow. tumida, Soul 



vol. II. 3 I 



