368 



CONIFERiE OF THE COAL PERIOD. 



[Ch. XXIV. 



underclays of the coal-seams of the Island of Cape Breton, in Nova 

 Scotia. 



In a specimen of one of these, represented in the annexed figure (fig. 

 481), the spread of the roots was 16 feet, and some of them sent out root- 

 lets, in all directions, into the surrounding clay. 



In the sea-chfts of the South Joggins in Nova Scotia I examined sev- 

 eral erect Sigillarice, in company with Mr. Dawson, and we found that 

 from the lower extremities of the trunk they sent out Stigmarice as roots. 

 All the stools of the fossil trees dug out by us divided into four parts, and 

 these again bifurcated, forming eight roots, which Avere also dichotomous 

 when traceable far enough. 



The manner of attachment of the fibres to the stem resembles that of a 

 ball and socket joint, the base of each rootlet being concave, and fitting 

 on to a tubercle (see figs. 482 and 483). Rows of these tubercles are 



Fig. 483. 



Fig. 482. 



Surface of another individual 

 of same species, showiii 

 form of tubercles. (Fosi 

 Flo. 34.) I 



StigmaHa ficoides^ Brong. One-fourth of nat. size. (Foss. Flo. 32.) 



arranged spirally round each root, which has always a medullary cavity 

 and woody texture, much resembling that of Sigillaria^ the structure of 

 the vessels being, like it, scalariform. 



Coniferoe. — The coniferous trees of this period are referred to five gen- 

 era ; the woody structure of some of them showing that they were allied 

 to the Araucarian division of pines, more than to any of our common 

 European firs. Some of their trunks exceeded 44 feet in height. Many, 

 if not all of them, seem to have differed from living Coniferce^ in having 

 large piths ; for Professor Williamson has demonstrated the fossil of the 

 coal-measures called Sternhergia to be the pith of these trees, or rather 

 the cast of cavities formed by the sinking or partial absorption of the 

 original medullary axis (see figs. 484 and 485). This peculiar type of 

 pith is observed in living plants of very different famihes, such as the com- 

 mon Walnut and the White Jasmine, in which the pith becomes so re- 

 duced as simply to form a thin lining of the medullary cavity, across 

 which transverse plates of pith extend horizontally, so as to divide the 

 cylindrical hollow into discoid interspaces. When these last have been 

 filled up with inorganic matter, they constitute an axis to which, before 

 their true nature was known, the provisional name of Sternhergia [d, d, 

 fig. 484) was given» 



