PLATE 82. 
Fig. 1. 707. 1 . Megalomus canadensis. ( Pag. 343.) 
1 a, b, c. Lateral views of casts, showing degrees of distortion. 
1 d. A dorsal view where the umbones have been depressed, leaving the space between them projecting. 
1 e. Dorsal view of a cast, where the umbones have been pressed forward much beyond their natural relation. 
1 /, g. Anterior and lateral views of a small specimen, preserving the shell. 
1 h. The interior of a part of the left valve, showing the large muscular impression and the two smaller pits 
above, with the folds on the thickened portion of the shell. 
1 i. The left valve of a specimen having the shell broken away, showing the numerous distinct lamina; of 
which it is composed. 
