PLATE VII. 
I )elt()[H>ct(‘n leniiisculus, Dana, 
External impression of a ri^ht \ ah e, exhil)iting the ^'ery large number of linear costa', 
and costate auricles. 
Internal cast of the united \ al\es. Above is the left or most convex valve, below the 
right or less (practicallv flat) valve. In the centre of the cardinal margin of the 
latter is thi' cast of the chondrophore, and below it the impressions of three 
supplementary muscular attachments. 
Localities. 
Eig. 1. ISTowra. 
Fig. 2. West Maitland. 
