Notes on Species of CorbiculadcB. 91 



cato ; pagina interna candidissima ; umbonibus paras, obliquis, acuti- 

 usculis, incurvis, approximates ; striis irregularibus, obsoletis ; epidermide 

 fuscescente vestita ; cardine angusto, incrassato ; dentibus cardinalibus 

 divergentibns, majoribus profunde canaliculatis ; dente laterali antico 

 conico, postico elongato, compresso. 



Long. 78 ; lat. 67; diam. 40 mill. 



Hob. ? Collect. Prime. 



The shell is transverse, rounded oval, very inequilateral, and 

 somewhat inflated in the centre of the discs. The anterior side 

 is produced and narrow, the posterior side is sub truncated. The 

 interior is white. The beaks are small, acute, they curve 

 inwardly and are approximate. The striae are irregular and 

 nearly obsolete. The epidermis is dusky and without polish. 

 The hinge is nearly straight and somewhat narrow. The car- 

 dinal teeth are elongated and narrow, the two principal ones 

 are very deeply bifurcated, the central tooth is very broad. The 

 lateral teeth, are very short and small, the anterior tooth is coni- 

 cal, the posterior is slightly elongated, narrow, and not much 

 raised. 



Compared with Cyrena suhlohata, this species is less heavy, 

 more inflated, the anterior is narrower and the hinge is less 

 broad and less strong. It differs from Cyrena sinuosa in being 

 anteriorly narrower, posteriorly broader, and in having the 

 hinge margin straighter. • 



Genus PISIDIUM. 

 l. Pisidiuni IVoY-Zelandicuiii, Prime. 



Pisidium Nov-Zelandkum, Prime. Proc. Zool. 1862. 



Prime Cat. 17. 1863. 



P. testa minuta, transversa, ovali, subobliqua, valde insequilaterali, 



