484 ASTARTIPjE. 



nut-brown epidermis on a colourless surface; the mus- 

 cular impressions are strongly marked; the dorsal area and 

 lunule are excavated; and the inner margin of the valves is 

 sometimes crenulated. 



Species of Astarte. 



arctica, Gray. mactracea, Linsl. 



Banksii, Leach. oblonga, Sow. Jun. 



bilunata, Conr. Pfeifferi, Phil. 



castanea, Say. Portlandica, Migh. 



compressa, Mont. quadrans, Gould. 



crebricostata, Forbes. semisulcata, Leach. 



elliptica, Brown. subsequilatera, Sow. Jan. 



f'usca, Poll. sulcata, Da Costa. 



intermedia, Sow. Jan. triangularis, Mont. 



lactea, Brod. and Sow. undata, Gould. 



Genus GOULDIA, C. B. Adams. 



Mantle-margin denticulated; siphons very short, dis- 

 united, their margins ciliated. Foot linguiform. 



Shell sub-trigonal, equivalve ; surface of valves con- 

 centrically striated or laminated ; lunule distinct. Hinge 

 composed of two primary teeth in one valve, and one in 

 the other; and two anterior, remote lateral teeth, one in 

 each valve. Pallial line simple, or very slightly sinuated. 



Syn. Thetis, C. B. Adams, not Soiverby. 



Ex. G. minima, Montagu, pi. 115, fig. 7. Shell, G. 

 Pacifica, C. B. Adams, fig. 7, a, 7, b. 



The species of Gouldia are few in number. One, G. 

 minima, is met with on the coasts of Britain, the others are 

 from the West Indies, and Mazatlan. 



