XV] HALONIA 137 



regularis is identical in the form of the cushions with the type 

 known as Lepidophloios laricinus. It is worthy of note that 

 under the name Halonia, Feistmantel^ figured a piece of de- 

 corticated axis characterised by two rows instead of the usual 

 spiral series of large cup-shaped scars. Recent researches have, 

 however, tended to break down the distinction between JJlo- 

 dendron and Halonia founded respectively on the biseriate 

 and spiral arrangement of the scars or tubercles. 



The interpretation of Halonial branches as cone-bearing 

 members of Lepidodendroid plants has passed into a generally 

 accepted statement of fact, but, so far as I know, only one 

 specimen has been figured in which strobili are seen attached 

 to an Halonia axis. This specimen, described by Grand'Eury^ 

 from the coal-field of Gard, is hardly sufficiently well-preserved 

 to constitute a demonstration of the correctness of the generally 

 received view, which, as is not uniisual, has been repeated by 

 one writer after another without due regard being paid to the 

 nature of the evidence on which the statement is based. It 

 may, indeed, be correct to describe Halonial branches as cone- 

 bearing, but there are certain considerations which make one 

 pause before unhesitatingly accepting this explanation. The 

 vascular strand which passes from the central cylinder of the 

 shoot to the tubercle or scar is composed of a solid rod of 

 xylem distinguished from the main stele by the absence of a 

 pith. In such petrified peduncles as have been discovered the 

 stele is of the meduUated type. The common occurrence of 

 strobili terminating slender branches of lepidodendroid plants, 

 though not a fatal objection to their attachment to Halonial 

 shoots, shows that in many cases the cones were borne at the tip 

 of leafy shoots. It may be that some of the Halonial scars are 

 in origin like those of the Ulodendron axes of Bothrodendron 

 and mark the position of deciduous vegetative branches. 



The first account of the anatomy of Halonia we owe to 

 Dawes'; this was followed by a fuller description by Binney^ 

 The history of our knowledge of this type of branch has been 

 given by Carruthers^, who expressed the opinion that Halonia 



1 Feistmantel loc. cit. PL xlvii. '■' Grand' Eury (90) A. 



3 Dawes (48). * Binney (72) ; see also Seward (99). ^ Carruthers (73^). 



