THE FOSSIL FLORA OF THE YORKSHIRE COAL FIELD. 



47 



circumference than at the base. It is seen, then, that the number of leaves borne is not 

 proportional to the size of the stem in girth. A transverse section of such a specimen 

 (presuming the internal organisation was preserved) would show at the base a much 

 less number of leaf traces than a section made immediately below the broken-over 

 summit, and a few feet above its base. 



In the upper portion of the trunk, five curious furrow-like grooves appear, and, deepen- 

 ing, give to the broken-over extremity of the tree the appearance as if it were about to 

 divide into five branches. These grooves may be due to shrinkage, but they seem to be 



Wnfc, 



'lout J/fi. 

 circvmfeftrtcc 



**<*■ ribs* 



ltj[ rilrs ■ 

 dOouf- S/t. 

 Circc/nrffrenee. 



7?i5&ecL Stem of Siailla rta J/ei<fht about 6ft- 6 irr 

 ■SuiiJtrfand! fftusrum 



too regular for that. I am not aware, however, that a dichotomising specimen of the 

 ribbed Sigillarise (Rhytidolepis section) has ever been discovered, though we know that 

 the Favularia section occasionally, though apparently very rarely, produced dichotomised 

 branches. Stur figures such an example.* Mr George Wild, Bardsley, has also shown 

 me a very fine example of a dichotomously branched stem of Sigillaria tessellata from 

 the Diamond Shaft, Bardsley Colliery, Lancashire. It was found in a bed of shale, about 

 50 feet below the New Mine (Middle Coal Measures).! 



* Die Culm Flora, Heft. ii. pi. xxv. figs. 2-3 {Sigillaria Eugenii, Stur). 



t Wild, " On Section of Shaft sunk through the Middle Coal Measures at Bardsley Colliery, and an interesting 

 Discovery of Calaniites," Manchester Geol. Soc, Feb. 2, 1886. 



