X1V PREFACE. 
The reports on Mammals, Fishes, Mollusks, and Insects are not yet completed, but 
could be finished in a few months, with an expenditure of not more than $500. 
For the preparation of the Geological Map specified in the act authorizing the Geo- 
logical Survey, an expenditure of perhaps $1,500 would be necessary. This would be 
consumed in making a review, in the field, of the ground gone over by the various 
assistants orf the Survey, in order to secure accuracy and consistency in the general 
results, and also to put the facts gathered from all sources on paper in a creditable 
style. ‘ 
From the foregoing statements it will be seen that— 
Ist. The field work of the Geological Survey is all done. 
2d. Reports have been prepared on the physical geography and general geological 
structure of the State; algo upon each of the eighty-eight counties into which the 
State is divided, and upon the principal fossil forms found in our rocks. 
3d. Of these reports—in addition to three reports of progress (1869, 1870, and 
1871)—two volumes on Geology, two on Paleontology, and two portfolios of maps and 
charts have been already published. | 
Ath. Of the complete series of the reports of the Survey, three volumes yet remain 
to be published, viz., one on Geology (already completed), one on Economie Geology, 
and another on Zoology, Botany, etc.—the two latter requiring some months of time 
and an appropriation of $5,000 before they can be finished. As these three unpub- 
lished volumes are without expensive illustrations, they can be issued in the same 
style with the volumes on Geology, at a cost not exceeding one dollar per copy. 
5th. A general Geological Map ef the State, five by six feet in dimensions, can be 
prepared at a cost not greater than $1,500. 
A few additional facts in regard to the Geological Survey may be of general interest. 
The survey began June 1, 1869, and it may be said to have continued to June 1, 1874, 
although the salaries of the officers were paid only to February 15 of that year. The 
total amount expended by the State on the Geological Survey has been $256,017.66, 
of which sum $86,764.17 were expended on the survey proper, and $169,253.49 on 
publication. | 
The publications of the Survey, including the volume now issued, consist of 116,000 
-volttiena 8vo, in part re-published .in German, containing numerous engraved plates, 
maps and sections, and three portfolios of charts. 
Although the aggregate cost of the Survey may seem to be large, it should be re- 
membered that all the expenditure except that for field and office work ($86,764.17) 
was returned to the people of Ohio in books which cost far less than similar volumes 
would be published for by private parties. As regards the practical benefits of the 
