BIVALVE SHELLS. 187 



maxiinae, ovato-rotundae, subsequales ; sinus pallii magnus, elon- 

 gatus, horizontalis ; ligamentum externum crassissimum, elon- 

 gatum, semi-cylindraeeum. 



Venus (spec), Sow. (1835) Proc. ZooL Soc. p. 42. 



D'Orb. (1839) Pal. Amer. Merid. p. 160. 



Jonas (1844), Moll. Beitr. p. 14. 



Philippi (1846), Ahbild. Conch. i. 

 Venerupis (spec), Deshayes (1839), Mag. de Zool. 



Grewingk (1848), Verh. Kais. Russ. Sfc. p. 351. 



Middendorf (1849), Malac. Ross. p. 567. 

 Tapes (spec), Sowerby (1852), Thes. Conch. 

 Saxidomus, Conrad (1837), Journ. Nat. Sci. Phil. 



Jay (1839 & 1851), Cat. Shells. 



Synopsis Specierum. 

 I. Species laevigatse, 1-6. 



II. Species sulcatae, 7 , 8. 



I. Species lcBvigatce. 



1. Saxidomus maximus. 



S. testa maxima, ponderosissima, oblongo-ovata, utrinque trun- 

 cato-rotundata, transversim sulcata, lutescente ; apicibus ad } 

 longitudinis sitis ; area lunulaque nuUis ; ligamento maximo, 

 prominente ; cardine tridentato ; pagina interna alba, postice 

 violaceo-suffusa ; margine integerrimo. 



Venus maxima, Anton, in Phil. Ahbild. Conch. ii. pl. 6. f. 1.' 

 Tapes maxima, Sow.jun. Thes. Conch. p. 692. pl. 150. f. 127. 



Hab. Nova Hollandia, ad Portum Lowe dictum. 



2. Saxidomus giganteus. 



S. testa ovato-oblonga, inaequilaterali, subcordiformi, transversim 

 striato-rugosa, postice hiante et subtruncata, cardine eroso, 

 nymphis magnis porrectis, marginibus integris. 



Venerupis gigantea, Desh. Rev. Zool. Soc. Cuv. 1839, p. 359 ; 



Mag. Zool. Guerin, Moll. pl. 43 (1841). 

 PuUastra gigantea, Catlow, Conch. Nom. p. 41. 



Hab. Mare Californiense. 



3. Saxidomus opacus. B.M. 



S. testa oblonga, subquadrata, turgida, concentrice substriata, 

 opaca, albida, pallidissime purpurascente ; latere buccaU bre- 



