Zoological Society. 71 



mata sinistrorsa, cylindrico-ovata, costellata, costulis distan- 

 tibus obliquis regularibus ; anfractibus sex, convexis, apice 

 subobtuso ; apertura rotundata ; peristomate duplicato, ex- 

 terno expanso reflexo, inter no recto, margine Jlexuoso. 

 Hab. On the banks of a river, Moreton Bay, E. Australia (Mr. 

 Strange) . 



This very pretty little shell agrees in all its characters with the 

 genus Biplommatina of Mr. Benson, after whom I have named it. 

 There is some difficulty in the location of this genus. Mr. Benson 

 says distinctly that the eyes are " on the posterior part of the tetita- 

 cula, at their base," but he says there is no operculum. Mr. Gray, 

 on the other hand, has described the operculum. The true position 

 is probably in Truncatellidce. 



Crassatella speciosa, A. Adams. C. testa transverse ovata, 

 subcequilaterali, jiallida, epidermide tenui fusca induta, con- 

 centrice plicata ; plicis confertis regularibus; latere postico 

 rotundato, antico acuminato subrostrato, angulato, margine 

 ventrali convexo, antice sinuato. 

 Hab. Bay of Campeachy. Mus. Cuming. 



The beaks in this species are acute and close together, and rather 

 more deeply plicate than the rest of the surface of the valves ; there 

 is an obtuse oblique and angular ridge extending from the umbones 

 to the ventral margin. 



Crassatella l,evis, A. Adams. C. testa ovato-transversa, 

 crassa, tumida, subcequilaterali, castanea, Icevigata, concentrice 

 striata, natibus subsulcatis ; latere postico rotundato, antico 

 producto subrostrato, margine oblique truncato, carina obtusa a 

 natibus ad basin decurrente instructo, posteriori sulcato, mar- 

 gine ventrali convexo antice sinuato. 

 Hab. La Guayra (M. Le Marie, French Navy). Mus. Cuming. 

 A large smooth pale chestnut shell beaked anteriorly and with a 

 prominent obtuse keel extending from the beaks to the fore part of 

 the ventral margin, and a broad shallow groove behind it ; the lunule 

 is ovate lanceolate, and the beaks are trausversely sulcate. 



Crassatella obscura, A. Adams. C. testa ovato-trigonali, 

 transversa, subcequilaterali, compressa, nigro-fusca, apicibus 

 transverse corrugata, ad umbonem plicata ; latere antico 

 rotundato, postico subtruncato ; margine valvarum intus cre- 

 nulato. 



Hab. China Seas, deep water. Mus. Cuming. 



A small brown-black species, with the valves only plicate near the 

 beaks and their inner margins finely crenulated. 



Crassatella bellula, A. Adams. C. testa ovato-trigonali, 

 subcequilaterali, carneo-fulva, immaculata, transverse con- 

 centrice plicata ; p>Ucis obtusis subconfertis regidaribus, antice 

 undulatis, subevanidis (sub lente rugulosis) ; latere postico 

 rotundato, antico vix truncato ; umbonibus acutis parvis ap- 

 proximatis. 



Hab. New Zealand (Mr. Hart). Mus. Cuming. 



