published figures can be introduced for comparative purposes. There are
two methods of studying the extinct life of the globe. Fossils are indices
of geological formations, and must be grouped by formations to subserve
the purpose of geologists. Fossils also have their biologic relations, and
should be studied and arranged in biologic groups. Under the plan adopted
by the Survey, the illustrations can be used over and over again for such
purposes when needed, as reproduction can be made at the small cost of
electrotyping. These same illustrations can be used by the public at large
in scientific periodicals, text-books, etc. All the illustrations made by
the Geological Survey are held for the public to be used in this manner.


LIBRARY.

The library of the Survey now contains more than 25,000 volumes, and is
rapidly growing by means of exchanges. It is found necessary to purchase
but few books. The librarian, Mr. C.C. Darwin, has a corps of assistants
engaged in bibliographic work. It is proposed to prepare a catalogue of
American and foreign publications upon American geology, which is to be a
general authors' catalogue. In addition to this, it is proposed to publish
bibliographies proper of special subjects constituting integral parts of
the science of geology.


PUBLICATIONS.

The publications of the Survey are in three series: Annual Reports,
Bulletins, and Monographs. The Annual Report constitutes a part of the
Report of the Secretary of the Interior for each year, but is a distinct
volume. This contains a brief summary of the purposes, plans, and