238 



PROCEEDINGS OP THE ACADEMY OF 

 I. 



[1884. 



Owing also to the fewness of the outcrops of the several 

 divisions of the Cretaceous, the boundaries had to be drawn from 

 such data as were accessible, which were in some cases abundant, 

 and in others entirely absent. Sufficient is known, however, to 

 make the writer confident of their general accuracy ; while the 

 missing links of knowledge could only be supplied by expensive 

 borings. 



