232 LYCOPODIALES [CH- 



development at the end of a rootlet. In 1842 Logan drew 

 attention to the almost complete monopolisation by Stigmana 

 of the underclays, the rock which as a general rule occurs below 

 a seam of coal. He wrote: "The grand distinguishing feature 

 of the underclays is the peculiar character of the vegetable 

 organic remains; they are always of one kind {Stigmaria 

 ficoides) and are so diffused throughout every part of the bed, 

 that by their uniform effect alone the clay is readily recognised 

 by the eye of the miners" This fact, which has played a very 

 conspicuous part in the perennial discussions on the origin of 

 coal, led to the almost general recognition of the underclays as 

 surface-soils of the Coal period forests. 



The next step was the discovery of Stigmaria in the Coal- 

 Measures of Lancashire and in the Carboniferous rocks of Cape 

 Breton, Nova Scotia, forming the basal branches of erect stems 

 identified by Binney^, Bowman^ and Richard Brown* as un- 

 doubted Sigillariae. In one case Brown found what he 

 considered to be convincing evidence of the continuity between 

 Stigmaria and Lepidodendron. 



In 1842 Hawkshaw^ described certain fossil trees, the largest 

 of which had a circumference at the base of 15 ft., discovered, in 

 the course of excavations for a railway in Lancashire, in soft shale 

 at right angles to the bedding. The surface features were not 

 sufficiently clear to enable hini to decide with certainty between 

 Sigillaria and Lepidodendron, but while inclining to the former, 

 it is interesting to note that the occurrence of numerous Lepido- 

 strobi near the root led him to recognise the possibility of a 

 connexion between the Stigmarian roots and Lepidodendron 

 stems. In 1846 Binney gave an account of similar trees found 

 at Dukinfield near Manchester: he spoke of one stem as un- 

 questionably a Sigillaria with vertical ribs, furrows, and scars, 

 about 15 inches high and 4 ft. 10 inches in circumference. He 

 expressed his conviction that "Sigillaria was a plant of an 

 aquatic nature^." Similar descriptions of rooted stems in the 

 Coal-Measures of Nova Scotia were published by Brown in 



1 Logan (42) p. 492. 2 Binney (44) ; (46). 3 Bowman (41). 



* Brown (45); (46); (47); (49). See also Dawson (66). 



5 Hawkshaw (42). « Binney (46) p. 393. 



