SYSTEMATIC ZOOLOGY AND NOMENCLATURE. 353 
serve any trace of organic structure. * As these trees, of course, 
have been petrified where they are found now, it would appear as 
if different mineral substances, held in solution in the water, had 
acted upon the woody tissue in different ways, according to its 
nature. In any case, it is evident that the petrification has been 
performed in various ways, by the slow action of the liquids pene- 
trating the sand, and not by the uniform crystallization of silica 
as it is now produced in the hot springs of volcanic origin. This 
is more evident, in considering silicified wood of our more recent 
formations.. Neither in the plains of Kansas and Nebraska, nor 
in Eastern Arkansas, nor in Mississippi and Ohio, where fossilized 
wood is found generally associated with a ferruginous argillaceous 
sandstone, is there any trace of volcanic agency. There is merely 
an evident relation of this kind of fossilization with the deposition 
of iron. In Ohio and Virginia, that part of the Mahoning sand- 
stone containing silicified trunks, borders, and perhaps overlays in 
part, the area where the richest and most numerous beds of iron 
ore have been deposited. In the recent formations, the fossilized 
wood is generally associated with the red or ferruginous clay. 
Even in the small area occupied by our Post Tertiary formation 
at Barlow, Ohio, disks of silicified fossil wood of dicotyledonous 
species are found in a bed of red ferruginous clay, associated with 
species of shells of the genus Anodonta, entirely transformed into 
a compact mass of oxyd of iron. 
SYSTEMATIC ZOOLOGY AND NOMENCLATURE. 
BY ALEXANDER AGASSIZ. 
Tue first requisite for the accurate discussion of any subject is 
an appropriate nomenclature. . The great influence Linnzeus exerted 
upon the progress of Zoology is due to the universal acceptance of 
the binomial system as a most concise and convenient method, a 
tool admirably adapted to bring order into the chaos of names of 
eae Wome eww okie On 6 ES apo o E ROE 
*Itis marked by inflated articulations, like a species of Anarthrocanna. Gopp., and 
is as yet the only specimen found in our Coal Measures which might be compared to 
the trunks seen by - Brongniart in the coal mines of St. Etienne, France, and com- 
pared to Bamboos, from their inflated articulations. (Lyell. Manuel, 4th ed., p. 319.) 
