I 



lite Carboniferous Formatiun. 37 



generall}' to have been about twenty or thirty feet in heiglit. The 

 cylindrical body called the lepidostrobus was most probably its 

 fruit. The calainites were a family closely allied to the modern 

 horsetails (equisetacine), and are characterized by their division 

 into joints or segments, and by their fluted stems. These plants 

 often grew to the height of twenty feet and upwards, and appear 

 to have grown in the same localities as the sigillaria. These 

 sigillaria were a large kind of tree, in some respects resembling 

 ferns; they occasionally reached the heiglit of seventy feet. The 

 stigmaria, to which so much importance is attached in respect to 

 the formation of coal, was first proved lo be the root of the 

 sigillaria, from a specimen embedded in a coalpit in Lancashire, 

 Identical specimens have since that frequently been found. The 

 rootlets which were formerly supposed to be their leaves, are now 

 shown by more perfect specimens to have been attached to the 

 root by fitting into deep cylindrical pits, rows of these tubercles 

 are arranged spirally round each root. There are five genera of 

 coniferous trees in the coal, in their structure they are unlike any 

 pines that now exist ; their fruit, the trigonocarpon, is a common 

 fossil in some coal-mines. Our present knowledge of fossil botany- 

 is too scanty to enable us to say whether the flora of the coal 

 belongs to a high or low type of organization. It appears to have 

 somewhat resembled the present flora of New Zealand. 



The formation of coal and the manner in which the plants 

 about which we have been speaking were imbedded, will be our 

 next point to consider. 



In various localities in the coalfields of the British Isles and 

 North America, trees have been found in a vertical position at 

 right angles to the plain of stratification ; trees thus found always 

 have a thin coating of the finest coal on the outside, their inside 

 being filled with sandstone or some other substance without any 

 trace of vegetable stricture, proving that they must have been 

 hollow when embedded; it is also a peculiar feature of these trees 

 that almost without exception they terminate downwards in seams 

 of coal, and that they never intersect a layer of that material. We 

 often find that the strata inside the trunk of a tree are different 

 from those without, and that there may be four or five beds of 

 sandstone and of shale inside the trunk while it pierces through a 

 single bed. This may be accounted for by the fact that the tree 

 would go on many years before it was thoroughly decayed, leaving 

 only the hollow bark, which would be filled up after the strata had 

 accumulated on the outside. Laying all these facts before us, we 

 will immediately come to the conclusions. 1. That there must 

 have been a vast body of fresh water continually subject to the 

 inundations of the sea. 2. That this body of water must have 



