PLANTS OF THE COAL. 



359 



these are known, but all of them quite different from living Conifers. 



They are mostly found : 1. In the form of trunks or logs in the sand- 

 stones above the coal-seams (Fig. 458) ; 2. 

 In the form of leaves, twigs, and leafy 

 branches in the roof-shale (Fig. 459) ; 3. In 

 the form of nut-like fruits of many kinds, 

 also in the roof-shale. But they are not 

 found as stumps and roots in situ in the 

 under-clay. From this we conclude that 



Fig. 459.— Araucarites gracili 

 duced(af ter Dawson). 



Fig. 460. 



-Section of same: b, woody wedges; c, pith and 

 pith-rays. 



they did not grow in the coal-swamps, but on the high ground about 

 them; that their leaves, small branches, and fruits were washed down 



Fig. 461. 



Fig. 462. 



Fig. 463. 



Fig. 464. 



Fig. 461-464.— Broad-Leaved Conifers. Living Congeners op some Coal-Plants: 461. Salis- 

 buria (Ginko), a branch. 462. Section of fruit. 463. A leaf, natural size. 464. Phyllocladus, 

 a branch. 



into the swamps, and their trunks were sometimes drifted down by 

 floods which overwhelmed and buried the coal. 



The trunks and woody branches are known to be those of Gym- 

 nosperms by the characteristic Gymnospermous structure of the wood 

 (Figs. 389, 390, page 328), especially the disk-like markings on longi- 



