12 
geological speculations grounded on the first oper 
be ultimately abandoned. | a cal Peat) oC 
The geographical distribution of ances remains, 
is an exceedingly curious inquiry. If accurately pur- 
sued, without reference to any preconceived theory, 
it will no doubt furnish much information as to the 
comparative ages of the different strata which com- 
pose the external crust of our planet—for that 
these strata were deposited or formed at periods of 
time more or less remote from each other, every one 
knows, to be a generally admitted geclogical fact. 
The occurrence of similar fossils in districts of coun- 
try remotely situated from each other, certainly pre- 
sents a phenomenon highly interesting to the specu- 
lative naturalist, and apparently indicates that the 
same powerful and general causes must have con- 
curred to produce these isomorphous depositions. 
No fossils have contributed more to this kind of in- 
formation, than those of shells, and as the mineralized 
species could not be satisfactorily studied, except by 
accurately comparing them with those which now 
inhabit our seas and continents; the search for shells, 
has become, from a simple amusement, the study of 
scientific men—or, as a writer remarks, “it was only 
after the period when it was perceived that geology © 
and ancient zoology were destined to be enlightened 
by their fossil remains, that this research passed from 
the hands of amateurs into those of naturalists.””* dae 
* We have not unfrequently noticed, both in the writings and — 
conversation of some geologists, a disposition to sneer at the — 
subsidiary branches of natural history. Mineralogy and con- — 
