218 R. L. JACK AND R. ETHERIDGE, JUN., ON PLANTS 



fine-grained matrix, or thin carbonaceous black films left by the soft 

 cellular tissue. They are ornamented either with a series of pucker- 

 like depressions, when viewed from the interior, or with a number 

 of wart-like eminences, when seen externally. These are the scars 

 of the points of issue of the vascular bundles passing to the leaves. 

 Along the margins of the stems are a series of spine- or thorn-like 

 projections, which may be the leaves themselves or only their per- 

 sistent bases, and are apparently arranged in spirally oblique rows. 

 They appear to be impunctate, although Mr. Carruthers thinks he has 

 detected a cicatrix in one or two of them. In some of the specimens, 

 around and near the scars, are a series of indistinct longitudinal 

 more or less parallel lines, or perhaps wrinkles. Either as a faint 

 impressed line on the surface of the micaceous matrix, or as a slender 

 flattened carbonaceous band, is seen the internal axis of the stems, 

 probably scalariform, and longitudinally striated. In fig. 1, this 

 axis may be seen extending beyond that part of the specimen from 

 which the cellular tissue has been removed ; fig. 2 represents what 

 appears to be a dichotomously branching stem. 



After submitting the specimens to a careful and close examina- 

 tion, we were convinced of their great resemblance to and affinity 

 with Dawson's genera Psilophyton (especially P. princeps), an&Arthro- 

 stigma*, our own conclusion being that the closest affinity was with 

 the latter genus. With the view of receiving support in this opinion, 

 or, on the other hand, correction, if necessary, the best specimens were 

 submitted to Mr. R. Etheridge, E.R.S., and Mr. W. Carruthers, E.R.S. 

 The latter has been kind enough to furnish us with some notes which 

 we now append, with his permission. We take this opportunity of 

 thanking Mr. Carruthers for his assistance. 



In Psilophyton princeps, Dn., the leaves are described as rudi- 

 mentary, or short, pointed, and rigid, becoming hard, spinous and 

 prominent ; in Arthrostigma gracile, Dn., as linear and rigid, with 

 circular bases, and nearly at right angles to the stems, sometimes 

 resembling spines. The spinous character is exhibited in our speci- 

 mens, the spines more closely resembling those of P. princeps in their 

 slightly curved form than those of A. gracile, which are almost at 

 right angles to the stem, and much less crowded and in equidistant 

 than in P. princeps. We at first thought that the scattered scars 

 were impunctate ; but Mr. Carruthers has detected what he thinks 

 may be a cicatrix scar in one or two of them. The following are his 

 remarks on the specimens submitted to him : — 



" They have a true Lepidodendroid structure. The axis consisted 

 of a slender column of vascular tissue ; the soft cellular tissue left 

 an undefined carbonaceous stain, except where the opening for the 

 passage out of the vascular bundles existed, the scars of which are 

 well seen from the inside. These are like Cyclostigma-m&rkinga ; 

 but in this specimen they are certainly the markings on the inner 

 surface of the false bark of these plants. The spines are, I believe, 

 the persistent bases of the leaves, not the leaves themselves, though 

 that is possible. But I see, I think, indications of their being bases 

 * Dawson, op. cit. pp. 37-42, pis. ix. & xiii. 



