458 Mr. James Sower by on a fossil Shell, §c. 



drawing, Tub. XXV. It represents a piece of chalk from Sus- 

 sex, which had a number of fragments apparently belonging to 

 one large shell, of the inside of which the chalk itself appears to 

 have been a nearly complete cast, showing the undulations as well 

 as the thickness and distance of the overhanging striae, all cor- 

 responding in proportion to smaller specimens : to this I have 

 added, in dots, the outer margin and the hinge in proper propor- 

 tions, fig. 1. Thus there is no doubt that these shells have been 

 very large ; and this leads to the conclusion, that they must have 

 grown very fast, or have been some time in a quiet situation, and 

 in immense quantities, before the catastrophe that enveloped 

 them in the chalk and in the infiltrated flints of large dimensions, 

 as well as in small pebbles. For more accurate information as 

 to the general outline of the large figure, I have added an inner 

 view of the Royston specimen, showing the hinge and parts of 

 the opposite shell broken, the lower edge appearing about the 

 middle, and the rest filled with chalk, fig. 2. ; also a view of the 

 outer part of the shell, showing the general contour, fig. 3. 



XXI. Softie 



