191-'.] STEVENSON— THE FORMATION OF COAL BEDS. 493 



visit with Hooker, he discovered Calamites with rootlets from 

 joints along the stem. These he describes in detail. 



Sorby'* relates that 8 large well preserved stumps had been 

 found at Wadsley, rooted in a clay-like shale; all of them Sigillaria 

 with Stiginaria roots. The tops are flat as though sawed off. The 

 largest stump is 5 feet 2 inches in diameter and a huge trunk is 

 prostrate alongside. In all, lo stems were seen in a space of 40 

 or 50 yards and all are cut off at the overlying sandstone, with 

 which they are filled. Sorby was much interested by the discovery 

 that the roots are arranged as are those of trees in Great Britain 

 of to-day — they are almost horizontal on the west side but pressed 

 down on the east, showing that the prevailing winds were the 

 same as now. Platt^^ described a tree rooted in an inferior firecla} 

 with the roots so arranged as to confirm Sorby's conclusions re- 

 specting the direction of the winds. W. B. Dawkins, in comment- 

 ing upon the paper, stated that he had made examination of the 

 tree and that his conclusion was the same with that of Sorby and 

 Piatt. 



Adamson^'' described a gigantic Sigillaria with 8 forked Stig- 

 inaria roots attached. The area embraced in the ramification of the 

 roots is 826 square feet ; it is difficult to conceive of removing this 

 mass by a landslide or on a level area so as to set it down with the 

 stem vertical and the roots outspread in normal position ; and the 

 difficulty is increased by the presence of other trees near by. This 

 tree was figured in 1887 by Williamson®^ who says that a larger 

 example was found near that described by Adamson, and that one 

 of the root divisions was traced 37 feet 4 inches to a sharp tip. 



'* H. C. Sorby, " On the Remains of a Fossil Forest in the Coal Meas- 

 ures of Wadsley, near Sheffield," Quart. Journ. Geol. Soc, Vol. XXXI., 

 1875, pp. 458-460. 



" S. S. Piatt, " Notes on a large Fossil Tree recently found in Shales of 

 the Coal Measures at Sparth Bottoms, Rochdale," Trans. Manch. Geol. Soc, 

 Vol. XXIII., 1895, pp. 65-69. 



'" S. B. Adamson, Rep. Brit. Assoc. Adv. Set. for 1886, p. 628. 



" W. C. Williamson, " A Monograph on the Morphology and Histology 

 of Stigmaria ficoides," Palceontograpli. Soc., vol. for 1886, pp. 45, 46, 48, 51, 

 PI. XV. 



