152 



The Naturalist. 



to all other seams. He was ready to admit that very large rivers 

 existed during former geological ages, and that the growth of 

 vegetation was then on a much larger scale than now ; but all our 

 coal seams, except those just named as containing much earthy 

 matter, favor the first-mentioned theory — that the vegetation forming 

 them grew on the spot where it is now found. This conclusion is 

 arrived at from the fact that every seam of coal (except those just 

 mentioned) has an underlying clay, in which the plants forming the 

 coal first took root, and this under-clay is now found to be literally 

 crammed with these roots and rootlets ; and then the fact that this 

 underclay always contains the roots, and the shale above the coal 

 seam always contains the leaves and branches of the coal-plants, is 

 good evidence that they grew on the spot. How often do we find 

 sigillaria standing erect with (stigmaria) its roots embedded in the 

 under clay, and that part of the tree which has passed through the 

 coal seam has been also changed into coal, while immediately above 

 the upper part of the tree towers away through the bed of shale, 

 sometimes 30 or 40 feet. 



Until within a few years, the fossil botanist had no light to guide 

 him in his researches into the character of the coal-plants, except the 

 outward markings on fragments of flattened stems and branches, and 

 this evidence is found to be very deceptive, since it has been dis- 

 covered that several specimens which had been named belonging 

 to so many different species are nothing more than different parts of 

 one and the same plant : as, for instance, the large tinnks of sigil- 

 laria, with stigmaria roots attached, found at Dukenfield, and now 

 preserved in the Museum, Manchester. 



What has been said of sigillaria may also be said of lepidodendron, 

 as well as all other fossil plants. Those sandstone casts of calamites 

 found in quarries have been represented as exhibiting all the char- 

 acters of the external appearance of the plant, whereas they are only 

 the casts of the inner parts of the calamite. He should be able to 

 show a section of a perfect calamite, with the bark attached. There 

 is, in the neighbourhood of Oldham, a seam of coal called the 

 foot*mine, which is very like in character to the hard bed here. Over 

 both seams are found large quantities of fossil marine shells, as 

 Nautili, Goniatites, Orthoceratites, Pectens, &g., and in both seams are 

 round nodules, containing fossil plants in a most beautiful state of 

 preservation. It is evident from the composition and character of 

 these nodules that the plants were calcified before bitumenisation set 



