Pleurodapis multicincta Clarke 



Fig. I, 2 Right and left valves 



3 Sculpture casts of conjoined valves with suppression of 



some of the posterior ridges. The abscission of the 

 umbones by pressure on the hinge-plates is noticeable 

 here, as on the succeeding figures 



4 The hinge, showing anterior muscle scars and a broad- 



ened platform behind, x 2 

 5, 6 Right valves, showing considerable divergence in the de- 

 velopment of the ridges 

 Locality: Ponta Grossa, Brazil 



174 



