76 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 28, 



laminated calcareous shales, rich in the phosphate of lime of fish- 

 remains, might be used for agricultural purposes. The highly 

 bituminous shales of Albert have been used for the manufacture of 

 hydrocarbons. The singular and anomalous bed or vein of highly 

 bituminous coaly matter at Albert is the most valuable deposit 

 hitherto found in this series. 



The absence of large beds of coal corresponds with the rarity of 

 terrestrial surfaces, and of remains of Sigillarioid and Coniferous 

 trees, the growth and acciunulation of which, and of the rank 

 undergrowth of Calamites, Poacites, and Perns, seem to have charac- 

 terized the coal-swamps of the middle coal-measures. 



The observations of Sir W. E. Logan on Stigmarian underclays, 

 in connexion with the subsequent discovery that the Stigmarice are 

 roots ofSigillaria, have established the connexion of these plants with 

 the production of coal ; and as long ago as 1845* I had convinced 

 myself, by microscopic investigation of the coal of the main seam of 

 Pictou, that this very thick bed consists, in great part, of the wood 

 of Sigillarioid and Coniferous trees, which last are proved, by the 

 Joggins section, to have actually grown in the coal-swamps. Re- 

 garding these as undoubted truths, I have been surprised to find so 

 much uncertainty on this subject expressed by late writers, and have, 

 in consequence, entered on a careful re- examination of the Pictou, 

 Sydney, and Joggins coals of the Middle Coal-measures, with the aid 

 of specimens collected during many years with this object, and 

 prepared by chemical methods, which, in some instances, enable me 

 to reproduce the organic tissue in all its original perfection. I am 

 not yet prepared to state all the results of this inquiry, but may 

 give the following as ascertained facts, bearing on the statements 

 above made respecting the flora of the Lower Coal-measures. 



1. By far the greater part of the tissues retaining structure are 

 Sigillarioid or Coniferous. 



2. The perforated tissue of the '' mineral charcoal " is merely an 

 altered condition of scalariform and disc-bearing vessels and cells. 



3. The differences in the laminae of coarse, bright, and fibrous coal 

 depend less on difference of material than on the amount of decay 

 the vegetable matter suffered before being finally excluded from 

 atmospheric influence. 



4. Some Observations on Stigmaria ficoides. 

 By E. W. Biifi^ET, Esq., E.R.S., F.G.S. 



[Plate IV.] 



During the past year it has been my good fortune to meet with 

 several specimens of this singular root, which throw some additional 

 light on the origia of its meduUary rays, — ^the nature of the vascular 

 bundles which were believed to be dispersed throughout its pith,— 

 and the structure of the central or vascular portion of its rootlet ; 



* Quart. Journ. Geol. Soc. vol. ii. p. 134. 



