40 STIGMARIA FICOIDES. 



conditions to those seen in Plate XIV, fig. 75, with the morphology of which this 

 part of Plate XII, fig. 40 is almost identical. 



Plate XI Y, fig. 77, is another of the many variable conditions in which we find 

 the external surface of a Stigmaria, and which were largely due to the shrivelling 

 of the specimen before its immersion in its muddy matrix, followed by external 

 pressure. Its configuration is virtually that of Plate XII, fig. 74. 



Plate XIII, fig. 78, represents a fine fragment in the Museum of the Natural 

 History Society of Newcastle. It is undoubtedly a portion of the plant to which 

 Goeppert gave the name of Stigmaria stellata, 1 though the rootlets given off from 

 the large symmetrically arranged tubercles are much less perfectly preserved than 

 in Goeppert's specimen. That this object has been a root with rootlets very 

 similar to those of Stigmaria ficoides appears probable. Whether or not it can be 

 generically united with Stigmaria is doubtful. We have other plants in the Coal- 

 Measures furnished with succulent rootlets besides Stigmaria, e.g. my genus 

 Amyelon. It appears to me that no plant should be regarded as a Stigmaria, the 

 internal organisation of which is not at least typically identical with that of 

 S. ficoides, and which consequently may be regarded legitimately as the probable 

 root of some Lepidodendroid or Sigillarian stem. We have no proof that either 

 the one or the other of these affinities exists in the object in question ; hence, whilst 

 recognising its unquestionable specific distinctness from Stigmaria ficoides, I should 

 prefer for the present to refer to it as Stigmaria (?) stellata. The Newcastle specimen 

 was apparently derived from one of the Gannister beds. I have more recently 

 received from Mr. Kidston, of Stirling, a cast of another similar specimen, found 

 loose in a Boulder Clay at Town-Head, Riccarton, in Ayrshire, by Mr. P. Wright, 

 of Galston. 



Conclusions. 



Having now described all the more important morphological and histological 

 features of the Stigmarian root which I have thus far observed, some questions 

 arise connected with its relations with other plants, extinct and living. 



The fact that large quantities of Stigmarian fragments have been found in 

 several localities unassociated with any Lepidodendroid or Sigillarian stems has led 

 some geologists 2 to " consider Stigmaria as originally representing floating stems 

 becoming roots under peculiar circumstances." 



We find nothing in Great Britain which supports this or any similar conclusion. 

 Hence British geologists are unanimous in regarding Stigmarioe as the roots alike 



' ' "Die Gattungen der fossilen Pflanzen,' tab. x, fig. 12, 1841. 



2 E. g. Lesquereux, ' Coal Flora of Pennsylvania,' vols. 1 and 2, p. 509. 



