MACTRELLA. 377 



and generally devoid of colour. The species are from 

 California, the Philippines, and Australia. 



Species of Mactrinula. 



angulifera, Desk. nasuta, Gould. 



angusta, Desk. ovalina, Lam. 



coruplauata, Desk. plicataria, Linn. 



dolabrata, Desk. Reevesii, Gray. 



Egena, Desk. striatula, Linn. 



explanata, Desh. vitrea, Gray. 

 Ia3vis, Chem. 



Genus MACTRELLA, Gray. 



Shell cordate, triangular, thin. Hinge with the cardinal 

 teeth small; hinder lateral teeth very short, rudimentary, 

 and near the cardinal ; ligament marginal, triangular, sepa- 

 rated from the cartilage-pit by a shelly ridge. Pallial sinus 

 deep, rounded. 



Syn. Papyrina, part, March. 



Ex. M. alata, Spengler, pi. 101, fig. 3, 3, a. 



Dr. Gray considers M. striatula, Linnseus, to be the same 

 as M. alata, Spengler, or M. carinata, Lamarck, which 

 latter is the type of his genus Mactrella. M. striatula, how- 

 ever, appears to belong to his genus Mactrinula, in which 

 we have therefore included it. The species of Mactrella 

 are from South America. 



Species of Mactrella. 

 alata, Spengl exoleta, Gray. 



