Castoroides Ohioensis. 385 
"There are several specimens, on the nature of which I feel 
much indecision ; they are chiefly from Mansfield. "These I 
shall reserve for the present for more light. 
Most of the vegetable impressions from Mansfield, when 
taken from the roof of the mine, were covered with a hard 
substance of a fresh olive-green color, which gave them the 
appearance of being yet alive. The color is now paler. This 
substance varies in thickness from 3, to à of an inch, is chiefly 
silex, and generally only covers the extent of the vegetable 
impression. It is thickest on the stem of Calamitee and 
Equisetaceæ. I have not yet subjected it to rigid analysis. 
The new and extensive field, opened by the working of the 
vast coal formations of the American continent, and the gen- 
eral progress of science, will undoubtedly engage many in the 
interesting pursuits of the chemical, microscopical and botani- 
cal examination of vegetable fossils; from the knowledge ac- 
quired in these, added to renewed labors in the field, we may 
reasonably hope for developments of the greatest interest to 
geology. 
Those who have studiedéthe subject must have perceived 
that, although plates give an idea of the outline of form and 
Venation of fossi] plants, yet, unless the artist himself is well 
in their distinctive characters, the specimens themselves 
are indispensable to, form correct opinions : by careful inspec- 
on of these, distinctions are much more readily apparent. 
ART. XXIX.— NOTICE OF THE GEOLOGICAL POSITION OF THE 
CRANIUM OF THE CASTOROIDES OHIOENSIS. . By James Hatt, Esq., 
One of the New York State Geologists, Also, ‘ 
AN ANATOMICAL DESCRIPTION OF THE SAME. By serm «in 
MAN, M. D., Prof. Anat. and Phys. in Med. Dep. of Hampden and Sidney 
lege. With three Plates. 
I. GEOLOGICAL POSITION. 
, Tue cranium was received from Rev. Benjamin Hall, D. D., 
President of Geneva College, and was discovered in a swamp 
