OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 
75 
parenchyma. The difference between these two tissues is quite as great as that which I 
have shown to exist between the corresponding ones of Aster ophy llites. In both cases 
the narrow prosenchyma of the aerial bark is converted into the modified parenchyma of 
the subterranean one. 
These resemblances to Lycopodiacece are further sustained by the nature of the fructi- 
fication. A German critic of my memoir on Volkmannia Dawsoni objected to my 
determination that it was a fruit of Asterophyllites on the ground that it appeared to be 
Lycopodiaceous in its aspect, and I have already pointed out the resemblance of its 
spores to the macrospores of Selaginella inceguifolia. At the first glance a verticillate 
jointed Ly copod appears an anomaly, but the jointed character of Asterophyllites is 
more apparent than real. In this respect the plant differs altogether from Catamites 
and JEquisetum. In Asterophyllites the node is a mere centrifugal expansion of the bark, 
since the central vascular axis pursues its course through the node altogether unaffected 
by its presence. In the two latter genera, on the other hand, the node affects the 
entire structure of the stem from its circumference to its innermost centre, altering 
equally the arrangements of the tissues in the bark, in the ligneous zone, and in the medulla. 
Such being the case, the merely verticillate arrangement of the leaves does not constitute 
a difficulty of much importance. In reference to this latter point, Professor Sachs 
writes to me : — 46 With regard to the question concerning the possibility of verticillate 
leaves in Lycopods, I believe that Lycopodium complanatum with its apparently decussate 
pairs, and Lycopodium selago with from three to five-membered apparent verticils, 
present analogies which are not to be entirely rejected.” And, after giving me further 
evidence in the same direction, he adds : — 44 I should accordingly find in the existence of 
verticillate leaves no reason for excluding a plant from the Lycopodiacece.' 1 ' 1 Cordially 
agreeing with these statements, I am at present of opinion that Asterophyllites and 
Sphenophyllum are plants allied in the closest possible manner, if they do not belong to 
one genus, and that they are to be regarded as somewhat aberrant members of the 
Lycopodiaceous family. In 1865 Dr. Dawson wrote concerning Sphenophyllum : — “ A 
beautiful specimen of Sphenophyllum emarginatum from New Brunswick, in the col- 
lection of Sir W. E. Logan, has enabled me to ascertain that its stem had a simple axis 
of one bundle of reticulato-scalarifonn vessels, like those of Tmesipteris as figured by 
Brongniart. These curious plants were no doubt cryptogamous, having a habit of 
growth like that of Eguisetacece , leaves like those of ferns or Marsiliacece , and fructifi- 
cation and structure like those of Lycopodiacece. They were closely allied to Astero- 
phyllites and Annularm’* . I need scarcely point out how this significant paragraph 
foreshadows part of what has . since been worked out with more elaborate detail by 
Professor Benault and myself. 
I have received from Professor Benault a copy of the “ Bapport ” of MM. Daubree 
and Brongniart upon his two memoirs, extracted from the 4 Comptes Bendus,’ t. lxxvi., 
which contains several important conclusions agreeing with those embodied in my 
* Quarterly Journal of Hie Geological Society, vol. xxii. p. 135. 
L 2 
