NATURAL HYDRAULIC INSTRUMENTS. 381 
These beautiful arrangements are, and ever 
have been, subservient to a common object, viz. 
the construction of hydraulic instruments of es- 
sential importance in the economy of creatures 
destined to move sometimes at the bottom, and 
at other times upon or near the surface of the 
sea. The delicate adjustments whereby the same 
principle is extended through so many grades 
and modifications of a single type, show the 
uniform and constant agency of some control- 
ling Intelligence ; and in searching for the origin 
of so much method and regularity amidst variety, 
the mind can only rest, when it has passed back, 
through the subordinate series of Second causes, 
to that great First Cause, which is found in the 
will and power of a common Creator. 
SECTION VIII. 
FORAMINATED POLYTHALAMOUS SHELLS. 
Nuimnulites, 
If the present were a tit occasion for such minute 
inquiries, the investigations of the various known 
species of Microscopic shells would unfold a 
series of contrivances having relation to the eco- 
nomy of the minute Cephalopods by which they 
were constructed, not less striking than those 
we have been examining in the shells of extinct 
