OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 
221 
mens which I have dissected, this geometric character is less obvious, the prosenchyma 
assuming in them the aspect so common in the bark of Stigmciria. On a fragment of 
the specimen fig. 33 there are indications that the bark has been very thick*, and that 
the portion represented by fig. 54, n, has not been far removed from the woody cylinder, 
though not being actually the innermost bark. The more external parts consist of 
radially arranged prosenchyma, but with an appearance of a second row of lenticular 
masses of large cells external to, and of smaller size than, that first described. I have 
noticed an approach to all these peculiar arrangements in some specimens of the bark of 
the common Stigmaria , which has evidently varied in the details of its structure, the 
variations possibly representing different genera and species of Lepidodendroid and 
Sigillarian plants. 
The only specimen which remains to be described is a very important one which I 
discovered in the cabinet of Mr. Nield. It is a cast or impression of the outer surface 
of a Favulciria (Plate XXXI. fig. 58), of a very strongly marked type and with very 
prominent leaf-scars. But its value consists in the exhibition of a transversely disposed 
verticil of lozenge-shaped scars (fig. 58, r) of a very remarkable character. The figure is 
enlarged to double the size of the original, in which, being a cast, what are now promi- 
nences represent corresponding depressions on the surface of the original bark. The 
centre of each lozenge-shaped disk consists of a small but prominent circular area ; this 
is surrounded by a ring of much smaller tubercles. Each disk is located at a .point where 
the vertical continuity of the lines of leaf-scars, always so regular in ordinary specimens, is 
broken, those below the disks being arranged in an alternating series with those above 
them. It is evident that we have here an hitherto undescribed feature in Favularia ; 
but, on discovering the specimen, it occurred to me that I had frequently observed, in the 
ordinary examples of the so-called “ decorticated ” Favularia ?, transverse bands crossing 
the stems, along which the regularity of the leaf-scars was interfered with and their 
distinctness blurred. Bkoxgniart has represented a specimen of this kind in tab. 155 
of his ‘ Histoire des Vegetaux Eossiles,’ though in his plate the break in the continuous 
lines of leaf-scars is less marked than is often the case. On examining the Favularia ? 
in my cabinet, I found one in which the subepidermal surface displayed the same inter- 
ruption, but over a part of which there remained the usual layer of coal representing 
the superficial tissues. On the exterior of the latter I found several scars similar to 
those of fig. 58. I think there can but be one conclusion respecting these cicatrices. 
They did not bear leaves, because these are represented by the usual scars above and 
below them. They are much too small for ordinary branches, besides which, verticils of 
branches are unknown things amongst these Sigillarian and Lepidodendroid plants. I 
conclude, therefore, that they supported a row of cones. Now it so happens that one of 
* I have more recently met with another example in which the outer prosenchymatous structure was nearly 
11 inch thick ; it was of the type containing a mixture of ordinary and fusiform cells, the latter elongated 
vertically and having a length of about -015. The arrangement exhibited irregularly alternating concentric 
layers of prosenchyma and parenchyma, the one gradually passing into the other. 
2 G 
MDCCCLXXII. 
