14 POSSIL PLANTS. 



logical Society,' previously quoted, came from, although from a different locality. This 

 specimen occurred in the " Halifax Hard Seam" or " Gannister Coal," at South Owram, 

 near Halifax. It was associated with Sigillaria, Stigmaria, Lepidodendron, Halonia, 

 BiploxyJon, Lepidostrohus, Tric/onocarpon, and other fossil Plants not well determined. 

 The above is about the order of relative abundance in which these plants occurred. 

 A portion of one of the nodules gave on analysis' — 



Sulphates of potash and soda ... ... ... ... r620 



Carbonate of lime ... ... ... ... ... ... 45"610 



26-910 



11-650 



Car bonate of magnesia 

 Bisulphide of iron ... 

 Oxides of iron 

 Silica... 

 Moisture 



13-578 

 0-230 

 0-402 



The stratum found lying immediately above the seam of coal in which the nodules 

 occurred was composed of black shale, containing large calcareous concretions, and for 

 about eighteen inches was one entire mass of fossil shells of the genera Aviculopeden, 

 Goniatites, OrtJioceras, and Posidonia. 



The beds occurred in the following (descending) order : 



Ft. In. 



1. Black shale, full of fossil shells and containing calcareous concretions ... 1 6 



2. Hahfax Hard Seam, with the nodules containing the fossil plants ... ... 2 0 



3. Floor of fireclay and gannister, full of Stigmaria ficoides. 



The fossil wood is found in nodules dispersed throughout the coal ; some being sphe- 

 rical, and others elongated and flattened ovals, varying in size from the bulk of a common 

 pea to eight and ten inches in diameter. In some portions of the seam of coal the nodules 

 are so numerous as to render it utterly useless ; and they are found to occur over a space 

 of several acres, and then for the most part to disappear, and again to occur as numerous 

 as ever. Por the distance of twenty-five to thirty miles the nodules are found in this seam 

 of coal in more or less abundance, but always containing nearly the same plants. Possil 

 shells are rarely met with in the nodules found in the coal ; but they occur abundantly in 

 the large calcareous concretions found in the roof of the " mines," and are there associated 

 Avith Badoxylon (containing Sternhergia piths) and Lepidostrobus. So far as my experience 

 extends, the occurrence of nodules in the coal is always associated with that of fossil 

 shells in the roof, and therefore may probably be owing to the presence of mineral matter 

 held in solution in water and precipitated upon, or aggregated around, certain centres in 

 the mass of vegetable matter now forming coal before the bituminization of such vegetables 



1 For this analysis I am indebted to the kindness of Dr. R. Angus Smith, F.R.S., who had it done in 

 bis laboratory by Mr. Browning. 



