Zoological Society. 71 



mata sinistrorsa, cylindrico-ovata^ costellatay costulis distan- 

 tibus obliquis reyularihus ; anfractibus sex^ convexis, apice 

 subobtuso ; apertura rotundata ; peristomate duplicator ex- 

 terna expanse rejlexo, interna recto^ maryine fiexuasa. 

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

 Stranye) . 



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 tenta- 

 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^ 

 suhcequilaterali, palliday epidermide tenui fusca induta, can- 

 centrice plicata ; plicis canfertis reyularibus; latere pastico 

 ratundatOy antico acuminata subrastratOy anyulatOy maryine 

 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^vis, A. Adams. C. testa ovato-transversay 

 crassay tufnida, subcequilateraliy castanea, Iceviyatay concentrice 

 striata, natibus subsulcatis ; latere postica ratundatOy antico 

 producta subrostrata, maryine oblique truncatOy carina ohtusa a 

 natibus ad basin decurrente instructOy posteriori sulcatOy mar- 

 yine ventrali convexo antice sinuato. 

 Hab. La Guayra {M. Le Marie y 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 transversely sulcate. 



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

 transversay subcequilateraliy compressay niyro-fuscay apicibus 

 transverse corruyata, ad umbanem plicata ; latere antico 

 rotundatOy postica subtruncato ; maryine 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-triyonaliy 

 sub(jequilateraliy carneo-fulva, immaculata, transverse con- 

 centrice plicata ; plicis obtusis subcanfertis reyularibuSy antice 

 undulatisy subevanidis (sub lente ruyulasis) ; latere pastico 

 rotundatOy antico vix truncato ; umbonibus acutis parvis ap- 

 proximatis. 



Hab. New Zealand {Mr ^ Hart)., Mus. Cuming. 



