PLATE 82. 



Fig. 1. 707. 1. Megalomus canadensis. ( Pag. 343.) 



la, b, c. Lateral vi(3ws of casts, showing degrees of distortion . 



1 d. A dorsal view where the timbones have been depressed, leaving the space between them projecting. 



1 e. Dorsal view of a cast, where the unibones 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. Tlie left valve of a specimen having the shell broken away, showing the numerous distinct laminse of 



which it is composed. 



