CAEDITA. 357 



The specimens In the Museum coUectioa are all ironstone casts, 

 and, the hinge-line not being visible, the generic position of this 

 species is doubtful also. In his diagnosis Mr. Etheridge, jun., 

 remarks: — "Our fossil approaches some of the flat forms of 

 Anodonta, and it is with these that it must be compared. The 

 more or less compressed valves, strong posterior angulation of the 

 dorsal margin, obliquely truncated posterior margin, and obliquely 

 rounded anterior margin, pending a knowledge of the dental 

 characters of the hinge, all point in this direction." 



Dimensions. — Height 57 mm. ; length 96 mm. 



Form, and Log. — " Tertiary" : Tasmania. 



96929. The type specimen, figured by Mr. Eobert Etheridge, 

 jun. ; from the Tamar river, between "Whirlpool Reach and George 

 Town. Presented hy Dr. J. Mdliyan. 



L. 6099. Two examples; locality (?). Purchased. 



Family CAEDITID^. 



Genus CARDITA, Bruguiere. 



[Ency. Meth. Vers. t. i. 1792, p. 401.] 



Shell oval, transverse, solid, inequilateral ; ornamented by salient 

 and frequently scaly costte ; lunule more or less depressed ; hinge 

 oblique; right valve carrying one small anterior lateral tooth and 

 two long posterior cardinal teeth ; left valve with a short anterior 

 cardinal tooth, one long posterior cardinal tooth, and one small 

 posterior lateral tooth ; muscle-scai's large and conspicuous ; pallial 

 line simple. 



As given by Bruguiere, Cardita is a mixture of several genera ; 

 following the rule applicable in such cases we must accept the 

 interpretation of Lamarck,' who was the first to break up Cardita, 

 and the type of the genus as given by that author is as here stated. 



It is impossible to satisfactorily separate Venericardia from 



' Mem. Soc. Ilist. Xat. Paris, 1779, p. 86. 



