88 
Yol. IV., part 1, p. 20, of the Quarterly Journal of Geology , 
is the following passage : “ That part of Stigmaria which 
intervened between the vascular axis and the bark, appears 
to have consisted of two kinds of tissue. These have, in most 
cases, been unfortunately destroyed, so that we cannot posi- 
tively know their true nature ; but they appear to have been 
of different characters, for there generally appears to he a 
well marked division. This is often shown in specimens 
composed of clay ironstone which have not been flattened, and 
the boundary line is about quarter an inch from the outside 
of the specimen. Most probably the outer zone has been 
composed of stronger tissue than the inner one 5 as is the case 
with well preserved specimens of Lepidodendron ” It is 
singular that such acute observers as those above named had 
not noticed this line of division, but it was no doubt owing to 
the imperfect specimens which they had examined. After 
the discovery of the outer radiating cylinder in Lepidodendron 
by Witham, and the same arrangement in Sigillari elegans 
by Brongniart, it was to be expected that such outer radiating 
cylinder would he found to exist in Stigmaria , if it were the 
root of Sigillaria. After an examination of a great number 
of specimens, the cabinet of Mr. James Bussell, of Chapel 
Hall, Airdrie, has afforded me four or five different Stigmaria , 
which give clear evidence of the existence of this outer 
radiating cylinder. They are all in clay ironstone, and have 
not been much compressed. He has kindly allowed me to 
slice two of the specimens, which afford decisive evidence of 
the existence of both an inner and an outer radiating cylinder. 
The space on the outside of the inner cylinder does not shew 
distinctly the bundles of vessels communicating with the 
rootlets, although there is some evidence of their former 
occurrence. The bell shaped orifices from which the rootlets 
sprang are well displayed, and the space between them is 
occupied by wedge shaped masses of elongated tubes of 
utricles arranged in radiating series, not to he distinguished 
