PREFACE. 



At the time of the publication of the first volume of the Palseontology 

 of Ohio it was supposed that all the new material collected by the Sur- 

 vey not there described would be included in the present volume, but in 

 the interval so much has been discovered that claimed a place in our Re- 

 port that it has been thought best to prepare a third volume on Paleeon- 

 tology, to accompany the third volume on Geology, already authorized. 

 This will be offered as Part II. of Volume III. of our Report, and should 

 its publication be ordered it will give a completeness and symmetry to 

 the records of the Survey which they would lack without it. 



With this proposed volume, the entire series of reports will consist 

 four volumes, of two parts each, or practically of eight volumes, of nearly 

 uniform size, viz., three on Geology, three on Palasontology, one on Eco- 

 nomic Geology, and one on Zoology, Botany, and Agriculture. 



The matter which will compose the third volume on Paljeontology is, 

 briefly, as follows : 



1. A general review of the Fossil Plants found in Ohio, with descrip- 

 tions of many new species. 



A large number of fossil fruits, and a few fossil plants, were described 

 and figured in our first volume, and a remarkably interesting though 

 isolated group of Lower Carboniferous plants will be found described by 

 Prof. Andrews in this volume, but no systematic review of our fossil flora 

 has yet been given to the public, and the greater number, and the most 

 interesting of the new sjjecies collected on the Survey, are as yet unde- 

 scribed. These are mostly from the Carboniferous rocks, but they also 

 include marine plants from the Lower and Upper Silurian, the Devonian 

 and Waverly, and also our oldest land plants, the tree-ferns and Arau- 

 carian pines, which grew on the Cincinnati island when it was sur- 

 rounded by the Devonian sea. 



