Derbyina smithi (Derby) 



Fig. 1,2 Copies of Derby's figures of the brachial apparatus 

 3 Ventral side of an internal cast, x 2 

 4, 5, 6 Ventral profile and dorsal views of an internal cast. 

 X 2 

 Locality: Ponta Grossa, Brazil 



Paranaia margarida (Derby) 



Fig. 7, 8 Derby's figures of the brachial apparatus 



Locality: Sant'Ana de Chapada, Mato Grosso, Brazil 



Cryptonella ? baini (Sharpe) 



Fig. 9 Cast of ventral valve 



10, II Dorsal views of internal casts 



12 Dorsal valve with hinge plate 



13 Enlargement of the surface of an inside cast, showing 



the filling of the shell punctures 

 Locality: Tybagy, Sao Paulo, Brazil 



Rensseiaeria falklandica Clarke 



Fig. 14 Internal cast of, ventral valve 

 15 Dorsal view of an internal cast 



Locality: Port Howard, East Falkland 



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