PLATE LII. 

 Megambonia caruiiformis. , 



r»ge 515. 

 Fig. 1. A'small individual preserving- the surface striae. 



Figs. 2, 3. Large specimens of the left valve preserving in a greater or less degree the surface charactei-s. 

 Figs. 4, 5. Casts of the interior of the right valve preserving some portions of the shell and the surface 



markings. 

 Fig. 6. A cardinal view of the specimen illustrated in figs. 2 and 5. 

 Fig. 7. A cast of the interior of a left valve, showing the anterior muscular impression. 

 Fig. 8. A gutta-percha impression from the preceding. 



Comiferous limestone. Clarence Hollow, Brie Co., iV. Y. 



Meoalodon cuLCULiiATus, Sowei'by. 



Fig. 9. The interior of a left valve, bhowiiig the muscular impression, teeth and hinge characters. 

 Devonian. Paffrath, Oennany. 



Megalomus Canadensis, Hall. 



Pig. 10. The interior of a left valve showing muscular scar, teeth and hinge characters. 

 Guelph. Canada West. 

 The figs. 9, 10 are given for comparison with the interior of the corresponding, MKaAHBONiA, 

 since generic identity has sometimes been claimed for these genera. 



