220 BIVALVE SIIELLS. 



(i. PisuM, Megerle, Gray, P. Z. S. 184/, u. 556. Sliell ovate- 

 wedgeshaped, inequilateral, truncated behind ; siphons of 

 animal short, united to the end. P. amnicum.'" — Gray, Ann. 

 Sf Mag. N. H. ser. 2. xi. 38. 



A. Dentes cardinales 3 • 3, anterior in valva dextra et posferior 

 in valva sinistra minores. Testa solida. Corbiculina, 

 Gray. 



Genus 1. CORBICULA. 



Animal ignotum. 



Testa ovato-trigona, subsequilaterahs, cordiformis, in utraque 

 valva cardo tridentato, dentibus divergentibus, dentes laterales 

 (hio aequales, compressi, tenui, transversim striati. Nymphae 

 breves basi rugosae ; impressiones musculares minores rotundatae 

 vel semilunares ; impressio palUi simplex. 



TelUna, Mull. Verm. Hist. n. 205. 



Vemis, Chemn. (1782) Conch. vi. 319. 



Cyclas (spec), Brug. (1792) Encycl. MeM.pl. 301, 302. 



Lamk. (1799) Essai d'une Class., Mem. de la Soc. d'Hist. 

 Nat. de Paris, i. 

 Cyrena (ex parte), Lafuk. (1818) An. s. Vert. v. 551. 

 Corbicula, Megerle (1811), Entwurf. p. 56. 



Gray (1847), Proc.Zool. Soc. p. 184 ; (1853) Ann. Sf Mag. 

 Nat. Hist. xi. 38. 

 Cyanocyclas, Blainv. (1818), Dict. Sc. Nat. xU. 280. 



" Mantle (of Corbicula consohrina), lobes free on the lower 

 edge and in front, united behind ; edge simple, with a series of 

 short conical beards just within the margin ; siphons two, very 

 short, separate, contractile ; apertures fringed with short crowded 

 conical beards; foot compressed, subquadrate, rather produced 

 in fi-ont ; body swoUen ; abductor muscles large, anterior oblong, 

 the hinder round, subtrigonal. 



" Labial tentacles 2 pair, large, broad, trigonal, equal ; giUs 

 ol)long, inner pair large, the outer about half the depth of the 

 inner, " 



a. Species Europm. 



1. CORBICULA PaNORMITANA. 



C. testa trigona, subsequilaterali, antice rotundata, postice angu- 

 Lata, transverse striata, disco depresso ; apicibus acutis, incur- 



