THE CARBONIFEROUS PERIOD. 



173 



envelope. The Stigmaria are generally found ramifying in 

 the " under-clay, " which forms the floor of a bed of coal, and 

 which represents the ancient soil upon which the Sigillarice grew. 

 The Lepidodendroids and Sigillarioids, though the first were 

 certainly, and the second possibly, Cryptogamic or flowerless 

 plants, must have constituted the main mass of the forests of 

 the Coal period; but we are not without evidence of the exist- 

 ence at the same time of genuine "trees," in the technical 

 sense of this term namely, flowering plants with large woody 



Fig. U2.Stigmariaflcoide*. Quarter natural size. Carboniferous 



stems. So far as is certainly known, all the true trees of the 

 Carboniferous formation were Conifers, allied to the existing 

 Pines and Firs. They are recognized by the great size and 

 concentric woody rings of their prostrate, rarely erect trunks, 

 and by the presence of disc-bearing fibres in their wood, as 

 demonstrated by the microscope ; and the principal genera 

 which have been recognized are Dadoxylon, Palaoxylon, 

 Araucarioxylon, and Pinites. Their fruit is not known with 

 absolute certainty, unless it be represented, as often conjectured, 

 by Trigonocarpon (fig. 113). The fruits known under this 

 name are nut-like, often of consider- 

 able size, and commonly three- or six- 

 angled. They probably originally 

 possessed a fleshy envelope; and if 

 truly referable to the Conifers, they 

 would indicate that these ancient 

 evergreens produced berries instead 

 of cones, and thus resembled the 

 modern Yews rather than the Pines. 

 It seems further, that the great 

 group of the Cycads, which are nearly allied to the Conifers, and 



Fig. 113. Triffonocnrpon 

 in nfinii, Coal-measures. Britain. 

 (After Lindley and Hutton.) 



