PLATE 5. 



Fig. 1. 46. 3. Maclukea magna. (Pag- 26.) 



I a. The upper surface partially denuded of the shell, showing the stria! with the smooth cast beneath. This 



is a perfect representation of the shell, except that the minute terminal volution is not shown, 

 t b. Side view of a cast of the shell, showing the depressed turbinate form and flat spire. 

 I e. View of the lower surface, somewhat worn ; showing the large umbilicus, which is partially filled with 



stony matter. 

 I d. A vertical section of the shell, near, but not directly through the centre of the spire ; showing several 



volutions, and the deep umbilicus. Such sections of the shell are not unusual in the rock, and they are 



generally vertical to the lines of deposition. 

 I e. A view of the shell worn down from the lower side, as it very commonly appears upon the weathered 



surfaces of the rock at Chazy. 



