228 LEPIDODENDREAE. 



strand is well preserved, and the tracheides with their structure can be 

 distinguished. The plant too described by Corda 1 as Lomatophloios 

 crassicaulis certainly belongs to this place ; all the characters which mark 

 the xylem-strand in this type are given in one of his figures 2 with 

 unmistakable distinctness. I have made assurance doubly sure by 

 examination of an original preparation of Corda in the botanical depart- 

 ment of the British Museum which was sent by him to R. Brown. It 

 shows only the very small central cylinder preserved in transparent stone, 

 the cell-walls of which have one and all been changed into opaque black 

 coal. The well-preserved teeth of the periphery projecting sharp and long 

 show distinctly that it belongs to the true Lepidodendron Harcourtii, and 

 not to L. Williamsoni. Since Corda found the outer surface in these 

 remains well preserved, there can be no doubt that Lepidophloios had the 

 structure of Lepidodendron Harcourtii. Whether this was the case with 

 all the species, and whether it was not also the case with true Lepidoden- 

 drae, remains an open question and is not prejudiced by Corda's discovery. 

 Young terminal ramifications of Lepidodendrae have been found here 

 and there, though not frequently, in the Lancashire and Yorkshire coal-field. 

 On the other hand they are found in great quantities in the plant-petrifactions 

 of Burntisland 3 and Laggan Bay in Arran 4 , Scotland, which were noticed in 

 the introductory chapter ; they are accompanied in both localities by larger 

 stems and branches, in which a strong secondary growth of wood has been 

 developed. Many fructifications also occur with these remains in Burnt- 

 island showing the same characteristic features, and it is natural to assume 

 with Williamson that the remains of the different parts of the same species 

 lie side by side in these deposits, though absolute proof of this cannot at 

 present be produced. To the fragments from Burntisland thus united to 

 one another Williamson has given the name Lepidophloios brevifolius, but 

 he has abstained from naming the Arran plants. If the stronger stems are 

 compared with the two preceding types, it appears that the Arran Lepido- 

 dendron is nearer the type of Lepidodendron Harcourtii, and that the 

 Burntisland forms may occupy an intermediate position between that type 

 and the type of L. vasculare. Its central strand is differentiated as in L. 

 Harcourtii, but it has not the peculiar angular outline, and the trace-bundles 

 seem, as in L. vasculare, to be only slightly carinately decurrent. It agrees 

 also with L. vasculare in the strong development of the secondary wood, 

 and this distinguishes it at the same time from a stem of true L. Harcourtii. 

 Unfortunately we know next to nothing of the characteristic features of the 

 surface in either form. In both cases the young branches show essentially 

 the same structure, only they are most strongly compressed in the remains 

 from Burntisland. The outer cylinder of the rind is preserved, and is 



1 Corda (1), tt. 1-4. 2 Corda (l),t. 3. 3 Williamson (1), in. 4 Williamson (1), x. 



