592 
ME. E. W. BINNEY ON SOME LOWER-COAL-SEAM FOSSIL PLANTS. 
The outer cylinder seems to surround the band of lax cellular tissue enveloping the 
inner cylinder, and appears something in the nature of a pith to it. The inner cylinder 
no doubt increased on its outside by encroaching on the zone of lax cellular tissue, as 
may be proved by comparing a young with an old specimen, No. 8 with No. 2. 
This outer zone of pseudo-wood increased externally like the inner cylinder, as is 
evident on comparing the younger with the older plant, the walls of the tubes of the 
latter being stronger, as might be expected to be the case ; and in both we have the 
singular phenomenon of a tree increasing externally in two different zones at the same 
time. 
As to the internal radiating cylinders described as occurring in the Diploxylon and 
Sigillaria , given in this communication, they are evidently like two different Stigmaria- 
cylinders, which afford no structure in their central axes, exactly resembling those 
figured by Dr. Hooker in his paper on Stigmaria jicoides printed in the ‘ Memoirs of 
the Geological Survey of Great Britain’*, in plate 2. figs. 14 & 5. In the latter we 
have the wedge-form masses of wood of a lunette shape running into the central axis, 
whilst in the former we have them separated by a sharp and well-defined line from the 
central axis. The identity of structure between Sigillaria and Diploxylon and these 
two Stigmarice is further proved by some specimens which have lately come under my 
notice. 
After the researches of Dr. Lindley, Professor Goeppert, Mr. Prestwich, Dr. Hooker 
and others, it really seemed that we had obtained almost a complete knowledge of the 
internal structure of Stigmaria. It is true that only Goeppert had seen the isolated 
bundles in the pith ; all the specimens of the other observers having been imperfect in 
that portion of the plant, and not giving indication of structure there f. In my own 
researches it has rarely fallen to my lot to meet with a Stigmaria showing any structure 
in the central axis, even where the small stems of Sigillaria vascularis , affording all the 
structure in that part, are in great abundance. 
Many years since, after an examination of a great number of specimens of Stigmaria 
in my collection, it occurred to me that an outer radiating cylinder would ultimately be 
discovered. In my remarks on Stigmaria % is the following passage: — “That part 
of Stigmaria which intervened between the vascular axis and the bark appears to have 
consisted of two different kinds of cellular tissue. These, in most cases, have been 
unfortunately destroyed, so that we cannot positively know their true nature ; but they 
appear to be of different characters, for there generally appears to be a well-marked 
division. This is often shown in specimens composed of clay ironstone which have not 
been flattened, and the boundary line is generally about a quarter of an inch from the 
outside of the specimen. Most probably the outer part of the zone has been composed 
of stronger tissue than the inner one, as is the case with well-preserved specimens of 
* Memoirs of the Geological Survey of Great Britain, vol. ii. part 1. 
t I liave written to Professor Goeppert for the purpose of obtaining further information as to the pith of 
this specimen, but I have not been successful in my endeavour. 
£ Quarterly Journal of the Geological Society, vol. iv. part 1. p. 20. 
