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the subject of more diversity of opinion amongst geologists 
than any other fossil plant ; from the different appearances it 
exhibits, and the supposed affinity it bore to various families 
of recent plants, with one of which it was desirable to 
arrange it. Owing, however, to the increasing atten- 
tion paid to fossil botany, and the value attached to 
examining specimens in situ, it is now satisfactorily proved 
that the fossils known under the name of Stigmaria are 
really the roots of other larger plants. For this investiga- 
tion and identification we owe much to the valuable re- 
searches of Mr. King in the Newcastle, Mr. Binney in the 
Lancashire, and Mr. Brown in the American coal fields. 
When I saw the first announcement, that Stigmaria had 
been found attached to the base of stems of Sigillaria so 
as to leave no doubt of their being the roots, by different 
individuals in distant localities, I felt persuaded it was 
only the beginning of this important discovery, from the 
fact that there is a great diversity in the appearance and 
external markings of the Stigmaria ficoides of geologists, 
so much so that, in some collections, the varieties have 
been specifically named. In some specimens, we see only a 
few depressed cavities or punctures, these distant and with- 
out apparent regularity ; in others, these areolae are deeper, 
more numerous, and with a distinct quincuncial arrange- 
ment. Sometimes, again, we see the areolae few and 
small, and the interstices running into elevated striae; and 
in one specimen belonging to this Society, the areolae are 
situated in decided hexagonal depressions. As there are 
several supposed species of Sigillaria which differ essentially 
in sculpture, why might not the roots of these different 
species also present a diversity of character, and thus the 
supposed varieties of Stigmaria prove really species, or, 
more properly speaking, the roots of distinct species of 
Sigillaria or some other large plant ? This conjecture 
