OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 333 
node, intersecting at once both some leaves and the commencement of a branch. 
The characteristic primary vascular, triangular, axis of the stem is seen at c, enclosed 
within a single exogenous series of vessels, d, as described in my previous memoir. 
The inner bark, g, has disappeared, but the outer bark, k, remains perfect. In 
the section previously figured the outline of the bark exhibited the three deep 
internodal furrows so common amongst these plants, but in the section now described 
these internodal furrows are. as is usual at the nodes, not present. On the lower 
margin of the figure we see in the outer bark the row of circular areolae, l, l, which 
are obviously points from which a corresponding number of vascular bundles have 
disappeared. At l' we find one of these circular areolae exactly opposite the base 
of the leaf to, and at T we find that the next similar areola is intersected more 
in the direction of its length and is actually being prolonged into the centre of 
the leaf m . There can be no doubt whatever that these areolae represent a corre- 
sponding number of primary vascular leaf-bundles, and that there was but one 
of these bundles to each leaf. That the objects to, to' are leaves and not branches is 
fortunately demonstrated by the fact that at x we have a small triangular bundle of 
the usual characteristic shape, which is obviously going off to supply a true branch. 
Since there are nine of the leaf-bundles in the left half of the section it is obvious that 
had that section also passed exactly through the node on the right hand side of 
the specimen, we should have had at least eighteen of these vascular bundles going 
off to a corresponding number of leaves. 
In determining whether this specimen is an Aster ophyllites or a Sphenophyllum, 
we must understand what the distinctive features of these two genera are. 
Brongniart defines Sphenophyllum thus : — “ Feuilles verticillees, cuneiformes, 
tronquees, entieres ou dentees, emarginees ou profondement dichotomies, quadrilobees 
a lobes plus ou moins profonds et greles.”* He adds that “dans quelques especes, 
les lobes cleviennent profonds, etroits et lineaires, et peuveut etre pris pour autant 
de feuilles clistinctes analogues a celles des Asterophyllites avec lesquelles il est 
alors facile de les confonclre,” and again he remarks, “ il faille une grande attention 
pour lie pas le confondre avec certaines especes d’ Asterophyllites. Il se rapproche, 
en effet, de ces plant es par la disposition verticillaire de ses feuilles, rnais il en differe par 
le nombre beaucoup moindre de ces organes a chaque verticille, 6 a 8 on 10, et 
par leur forme qui est triangulaire, tronquee an sonnnet, ou dentes et lobes 
quelquefois tres profondement.” Now, the leaves of my plants exhibit none of these 
features, being long, linear, and entire, and from eighteen to twenty -four in each verticil. 
It is impossible to look at the two leaves to and m of fig. 27 without seeing that 
they show no signs of becoming cuneiform. Still less can we examine those described 
in my memoir, Part V., and figured in Plate 3, examples of which I made sections 
in every possible direction, without arriving at the same conclusion. Messrs. 
* ‘ Tableau des Genres de Vegetaux Fossiles,’ p. 52. 
