38 
this kind. We may perchance meet with better and better 
specimens, but often a mere memorandum is all that may be 
found for ages, and such will frequently serve as a geologi- 
cal identification of strata, which is often very convenient, 
and it will be highly desirable that those who meet with 
these or common subjects, will notice them wherever they 
be, that the Author or others may be able to point out every 
place of their occurrence. 
