LEPIDOPHLOIOS, AND ON THE BRITISH SPECIES OF THE GENUS. 531 



Certain parts of Corda's generic description — that relating to the structure of the 

 cylinder which occurred in his specimen and the fructification— may be left out of the 

 discussion as to the generic relationship of Lomatophloios with Lepidophloios. There is 

 really no conclusive evidence that the Sternbergia pith, which was inserted in the stem 

 studied by Corda, belonged to the bark which enclosed it, and, on the other hand, there 

 is much evidence that it did not, and this view has been taken by Solms-Laubach.* 



Anyone who has examined transverse sections of the large trunks of Lycopods, which 

 occur in an upright position at Laggan Bay, Arran, and which contain in the infilling 

 volcanic ash numerous vascular bundles of different plants which had been floated into 

 them after the original tissue which had composed the stem had disappeared by decay, 

 can easily appreciate the unsatisfactory nature of the evidence on which Corda has 

 associated an axis with a Sternbergian pith with a plant having the known bark of a 

 Lycopod ; and that a mistake has been made here is, I think, conclusively proved by the 

 fact that the specimen described by Professor Williamson as Lepidodendron fuli- 

 ginosumi has been shown by an example on which the bark was preserved to be the 

 Lepidophloios acerosus, L. and H., sp.,| with which I believe Corda's Lomatophloios 

 crassicaulis is synonymous. 



In none of the specimens of Lepidodendron fuliginosum which were described by 

 Williamson was there a Sternbergian pith, but in all respects the structure of the stem 

 conforms to the ordinary type of structure of the Carboniferous Lepidodendrece. 



Therefore, in comparing the generic characters of Lomatophloios with those of the 

 older genus Lepidophloios, we must dismiss from our minds all characters derived from 

 the Sternbergia axis, which Corda found within his specimen. 



Leaving out, therefore, those characters adopted by Corda, but which do not belong 

 to the outer envelope of his specimen, the generic characters of Lomatophloios would 

 then be — 



Bark scaly, leaf-bearing scales placed in £ spiral series attached below, 



fleshy, thick, truncate, erecto-patent, imbricate, with rhomboidal cicatrice provided with 



three vascular cicatricules, horizontally placed, central Leaves linear with 



single medial nerve. 



The whole difference, then, between the genus Lepidophloios and the genus Lomato- 

 phloios rests on the position of the leaf cicatrice : in the former it is situated at the base 

 of the cushion, and in the latter at the top. In other words, to put the matter more 

 correctly, in Lepidophloios the leaf-cushions are directed downwards, and in Lomato- 

 phloios they are directed upwards. Upon this single difference the two genera stand, 

 and it appears to me to be far too insignificant a character for the separation of allied 

 species into different genera, even if the character were constant ; but I hope to show 

 that this supposed difference does not hold, even specifically. 



* Fossil Botany, p. 212, Oxford, 1891. 



+ Proc. Boy. Soc, vol. xlii. p. 6. 



\ Cash and Lomax Bep. Brit. Assoc. Leeds, 1890, p. 810 (1891). 



