362 



FERNS — LEPIDODENDRON. 



[Cii. xxiy. 



called Caulopteris, by Lindley, and the Psaronius of the upper or newest 

 coal measures, before alluded to (p. 3 5 '7). 



All the recent tree-ferns belong to one tribe [Polypodiacece), and to ? 

 small number only of genera in that tribe, in which the surface of the 

 trunk is marked with scars, or cicatrices, left after the fall of the fronds. 

 These scars resemble those of Caulopteris (see fig. 466). No less than 

 250 ferns have already been obtained from the coal-strata ; and, even if 

 we make some reduction on the ground of varieties which have been mis- 

 taken, in the absence of their fructification, for species, still the result is 

 singular, because the whole of Europe aff'ords at present no more than 60 

 indigenous species. 



Fig. 468. 



Living tree-ferns of diiTerent genera. (Ad. Brong.) 

 Fig. 407. Tree-fern from Isle of Bourbon. 

 Fig. 408. Ci/athea glauca, Mauritius. 

 Fig. 409. Tree-fern from Brazil. 



Lepidodendron. — About 40 species of fossil plants of the Coal have 

 been referred to this genus. They consist of cylindrical stems or trunks, 

 covered with leaf-scars. In their mode of branching, they are always di- 

 chotomous (see fig. 471). They are considered by Brongniart and Hooker 

 to belong to the Lycopodiacece, plants of this family bearing cones, with 

 similar sporangia and spores (fig. 474). Most of them grew to the size 

 of large trees. .The figures 470-472 represent a fossil Lepidodendron^ 49 

 feet long, found in Jarrow Colliery, near Newcastle, lying in shale parallel 

 to the planes of stratification. Fragments of others, found in the same 

 shale, indicate, by the size of the rhomboidal scars which cover them, a 

 still greater magnitude. The living club-mosses, of which there are about 

 200 species, are abundant in tropical climates, where one species is some- 

 times met with attaining a height of 3 feet. They usually creep on the 

 ground, but some stand erect, as the L. densum, from New Zealand 

 (fig. 473). 



