CONCHYLIA— DITHYE^. xxiii. 



10. Sphenia. 



1. Binghami, cuneata, dente concavo obliquo injlexo. 



wedge-shaped, with the concave tooth oblique 

 and inflected. 



2. Swainsoni, ovata, dente concavo horizontali-protenso . 



oval, with the concave tooth projecting horizon- 

 tally inwards. 



3. decussata, decussatim striata. 



with decussate striae. 



11. CoRBULA. 



1. Nucleus, Corbula. 



12. Pandora. 

 1. margaritacea. Pandora. 



13. Panop>ea. 

 1. Glycymeris, Panopcsa. 



14. Anatina. 

 * Cochlearibus ohliquis. 



with the spoon-shaped teeth oblique. 



1. convexa, oblonga, cochlearibus integerrimis. 



oblong, with the teeth very entire. 



2. pubescens,o&Zowgfa cochlearibus emarginatis. 



oblong, with a notch on the teeth. 



3. truncata, cuneata umbonibus subterminalibus. 



wedge-shaped, with the beaks nearly terminal, 



