General Classification of the Pelecypoda. 101 



LP = lateral posterior lamella. 

 LA=lateral anterior lamella, 

 CA = anterior cardinal. 



rt = anterior portion of an anterior cardinal. 



A= posterior portion of an anterior t-ardinal. 



Left valve. li/i//it valrc. 



LP VI li?t. LA VI 



A. LP IV ligt. LA IV 

 LP II ligt. LA II 



LP VI ligt. CA6 LA VI 



B. LP IV ligt. CA4 LA IV 

 LP 11 ligt. CA 2 LA II 



LP VI ligt. £/> 6_<^r LA \l 



C. LP IV ligt. 4A \ji_ LA IV 

 LP II ligt. '2 J) 2 a LAir 



LV_V ligt. LP V 

 LAIIIli-t. LP III 



L.V I ligt. LP I 



LA V CA 5 ligt. LP V 



LA III CAa iigt. LPiir 



LAI CAl ligt. LPI 



LA Y oa^ ri_h_]l^t. LPV 

 LA III -S^^ 3 6 ligt. LP III 

 LA I CA 1 ligt. LPI 



Diagrams showing the relation of the teeth 

 according to Bernard. 



A. Stage showing primary lamellae only. 



B. Stage showing development of anterior cardinals and laterals. 



C. Stage showing bifurcation of the anterior cardinals. 



Bernard provisionally divided the Heterodonta into two 

 classes. He did not hold these classes to be strictly natural 

 oneSj but he made them for the sake of convenience. 



Subdicisions of the Heterodonta. 



A. The Cyrina type, where the CA. I is present, and CA II 



is divided into 2 a and 2 b. 



B. The Lwciwa type, where the first cardinal is undeveloped 



and the second cardinal is consequently simple. 



Families iti Bernard's 07'ders and Suborders. 

 Heterodonta. 

 Pliodonta. 



Mactridfs : Mactra, Schizodesma, Lutraria,. Merope, 



Schizothoerus, Eastonia, Kaeta. 

 Scrobicularidce : Cumiugia, Semele, Scrobiciilaria. 



