Figs. 42 & 43. Inoceramus connecting /. lamarcki with /. involutus. Upper 

 Chalk : 42, anterior ; 43, posterior. 44 & 45. /. involutus Sow., Mi- 

 craster cor-anguinum Zone : 44, anterior ; 45, posterior. All (3) half 

 of the natural size. 



anterior area which at first became concave and then decreased in 

 size, ultimately disappearing (figs, 44 & 46). The right valve, in 

 some forms of /. involutus, is moderately convex, with strong folds 

 and a concave anterior area, and agrees with the right valve of one 

 variety of 7. lamarcki ^ ; in other forms which have departed farther 



H. Woods, op. cit. p. 325 & text-fig. 85. 



