Prof. E. W. Clay pole— Fossil Tree from the IT. Silurian. 559 



Upper and Lower Silurian beds, wliicli are here in juxtaposition and 

 conformable, though marked at their junction by a great palseonto- 

 logical break. It becomes therefore necessary to set forth the 

 evidence for its asserted age. 



The oldest known tree, Gli/ptodendron Eatonense,TJ. Silm-ian (Clinton), Eaton, 

 Preble Co., Ohio, U.S. 



In the first place the general appearance of the stone is sufficient 

 to satisfy any one practically familiar with the locality that it belongs 

 to the horizon above mentioned. It is a slab of yellow, coarse- 

 grained, Encrinital limestone, considerably weathered, exactly like 

 the limestone of that date at Eaton, and generally on the outcrop 

 around the Cincinnati exposure. In the second place, it contains on 

 its face one of the commonest of the Corals found in the " Clinton " 

 of the Ohio Survey, and closely resembling, if not identical with, 

 ChcBtetes hjcoperdon (Hall), from the Hudson Kiver and Clinton 

 groups in New York, and figured in the first and second volumes 

 of the Report of the New York Survey. Thirdly, from the 

 back of the stone I chipped out a piece containing a small Illceniis, 

 the young of Illcenus I)aytonensis (Hall and Whitfield), Clinton 

 group, " Ohio Palaeontology," vol. ii. ; or possibly of I. Varriensis 

 (Mur.), /. ioxus (Hall). As the last-mentioned genus is not recog- 

 nized above the Niagara (Wenlock) Group, this specimen is suffi- 

 cient to determine the age of the stone, and therefore of its contained 

 fossil.^ 



At the outset of my examination, I was inclined to place the fossil 

 in the genus Lepidodendron ; but further study has convinced me 

 that it cannot rightly be referred to that plant, and I therefore put it 

 by itself in a new genus, thus defined : — 



Glyptodendkon. Tree-like stem cylindrical ; surface marked 

 with two parallel sets of ridges running spirally up the stem in 

 opposite directions, crossing each other and thus forming rhomboidal 



1 The fossil was exhibited, and an address given upon it, at a meeting of the 

 Natui-al History Society of Cincinnati on January 1, 1878. Many gentlemen well 

 acquainted ■nith the geology of this region were there present, and the evidence then 

 and there submitted was unanimously considered conclusive on the age and relations 

 of the fossil.— E. W. C. 



