454 THE CARBONIFEROUS SYSTEM. 



ledge, it is impossible to identify with this species. I suppose that L. 

 elegans resembles the present species in its mode of growth, at least 

 if the large-scarred specimens attributed to it are really of the same 

 species. L. dichotomum ( = L. Sternbergii) also resembles it to some ' 

 extent (Fig. 169, E). 



L. Pictoense, Dawson. — This species I described as follows, from 

 young stems, in my " Synopsis of the Coal-plants of Nova Scotia : " — 

 "Areoles contiguous, prominent, separated in young stems by a nar- 

 row line, long-oval, acuminate ; breadth to length as 1 to 3, or less ; 

 lower half obliquely wrinkled, especially at one side. Middle line 

 indistinct. Leaf-scar at upper end of areole, srrMll, triangular, with 

 . traces of three vascular points, nearly confluent. Length of areole 

 about 0-5 inch." 



Additional specimens from Sydney show that in old trunks of this 

 species the areoles do not enlarge, but the bark becomes split into 

 strips. I have reason to think that a new species from Nova Scotia, 

 which I shall describe in the sequel, L. personatum, agrees with it in 

 this respect (Fig. 169, A, B). 



The Lepidodendra resemble each other too closely to admit of good 

 sub-generic distinction. The grounds on which the distinction of 

 Sagenaria and Aspidiaria is founded are quite worthless, the apparent 

 position of the vascular scars in the areoles depending on accidents of 

 preservation much more than on original differences. The genus Knor- 

 ria includes many peculiar conditions of decorticated Lepidodendra. 



In regard to the accumulation of coal, Lepidodendra, when present, 

 appear under the same conditions with Sigillariai, the outer bark being 

 converted into shining coal, and the scalariform axis appearing as 

 mineral charcoal of a more loose and powdery quality than that 

 derived from Sigillaria. On the planes of lamination of the coal the 

 furrowed bark of old trunks can scarcely be distinguished from that 

 of old Sigillaria; (Fig. 170, B, C). 



2. Lepidophloios. — Under this generic name, established by Stern- 

 berg, I propose to include those Lycopodiaceous trees of the Coal 

 measures which have thick branches, transversely elongated leaf- 

 scars, each with three vascular points and placed on elevated or 

 scale-like protuberances, long one-nerved leaves, and large lateral 

 strobiles in vertical rows or spirally disposed. Their structure 

 resembles that of Lepidodendron, consisting of a Sternbergia pith, a 

 slender axis of large scalariform vessels, giving off from its surface 

 bundles of smaller vessels to the leaves, a veiy thick cellular bark, 

 and a thin dense outer bark, having some elongated cells or bast 

 tissue on its inner side. 



