176 MESSRS. KIRKBY AND DUFF ON THE 



individuals, which must also materially affect the nature of the 

 coal."* 



We draw attention to these views of Dr. Geinitz because they 

 relate to a question of considerable importance — not only to 

 the palaeontologist, but to those who are practically engaged 

 in coal-mining. For as a question of science, it is certainly not 

 generally known that any regular succession of plant-life obtained 

 during the period of the Coal Measures and other formations of 

 the Carboniferous system ; and it is as certainly a thing to be 

 desired by coal-owners, and those in their employ, that such a 

 succession of plant-life should be determined and made known 

 to them. If it could be shown that different seams of coal are 

 characterised by different kinds of fossil plants — that the lower 

 seams, for instance, are marked by Sigillarice, the middle seams 

 by Calamites, and the upper by ferns, mining men would then 

 have something better to guide them in the identification of 

 coals than they are now possessed of, and it would be as easy 

 to determine the relative position of any portion of a coal-field 

 as it generally is now to distinguish one formation from another 

 by its fossil contents. 



We were led, from the remarks of Dr. Geinitz on this ques- 

 tion, to examine whether the coals of the Etherley district ap- 

 peared to be marked by any special group or groups of fossil 

 plants. Whether, for example, the "Brockwell" could be dis- 

 tinguished from the "Five Quarter" by its fossils; or whether 

 the prevailing fossils of both pertained to a distinct type; or 

 whether they differed in any way from those already described 

 from higher Measures of the coal-field. The following diagrams 

 and remarks are the results of this examination, which was 

 made from time to time as fossiliferous patches of roof came 

 under our notice, and other circumstances afforded facilities for 

 the investigation. 



Fig. 12 shows the relative position of the principal points 

 where fossils were collected from the roof of the Brockwell 

 seam, excepting in one instance where we had not an opportu- 

 nity of collecting fossils in situ, but only from material specially 



* Quart. Jour. Geol. Soc, 1857, p. 105. 



