CARBONIFEROUS. 171 



alone, one would think, were sufficient to place the affinities of Halonia 

 outside the circle of discussion, but notwithstanding the conclusive evidence 

 they afford on this point, the view held by these writers has not been univer- 

 .sally accepted.* 



Mr. Carruthers has also figured a specimen of Halonia attached to Lepi- 

 dophloios,^ which is in the Collection. The conclusion arrived at by him 

 was very similar to that mentioned by Feistmantel, that Halonia was only a 

 condition of Lepidophloios. Both on the Halonian-branch and the main stem 

 of this example some of the characteristic leaf-scars of Lepidophloios are 

 shown. Those on the Halonia portion are normal in form and point down- 

 wards, but on the main stem from some cause, perhaps pressure or distortion 

 during or after mineralisation, the leaf -scars are arranged at right angles to 

 the direction they ordinarily hold on the stem ; hence the two lateral angles 

 of the leaf-scar lie parallel to the direction of growth, and the scar of the 

 vascular bundle so twisted round, and occupies one of the lateral angles. 



In his last memoir on the " Organisation of Fossil Plants of the Coal 

 Measures,"! Dr. Williamson gives a figure (pi. xxxiv.) of Halonia attached to 

 a Lycopodiaceous stem. He says, " In my second memoir (Phil. Trans. 1872, 

 p. 222), read in June, 1871, I said, ' I have little doubt but that Halonia 

 was a fruiting branch of a Lepidodendron ;' and in a note added in April, 1872, 

 I affirmed absolutely, ' First, that Halonia belongs to the upper branches, of a 

 Lepidodendroid tree, consequently it cannot be a root ;' 'secondly, we learn 

 that Halonia is a specialised branch of a Lepidodendroid tree that is not itself 

 a Halonia.' " . . . " The specimen now described is unquestionably not a 

 Lomatophloios, but a true Lepidodendron." In describing his specimen, he 

 says further (p. 468), that at the lower portion of the branch the leaf -scars 

 have exactly the same form as those of L. selaginoides and L. elegans, Lindley 

 and Hutton. I have already mentioned that the leaf-scars on the specimen 

 described by Mr. Carruthers are so turned round on the stem that instead of 

 their greater diameter being transverse to the stem, as is normally the case 

 in Lepidophloios, it is vertical. Dr. Williamson's figure does not show clearly 

 the form of the scars further than that the vertical diameter of those on the 

 lower part of the stem seems greater than their transverse breadth. The leaf- 

 scars towards the upper portions of the specimen are rhomboidal. I am 

 inclined to think there is here a case of distorted leaf -scars on the lower part 

 of the fossil, similar to that occurring in Mr. Carruthers' specimen, where, 

 notwithstanding this peculiarity, the fossil is clearly identifiable as Lepido- 

 phloios laricinus. 



With such an imperfectly preserved example as Dr. Williamson's appears 

 to be, any conclusion derived from it is of doubtful value, and though from 

 an examination of his plate one cannot affirm his fossil is a Lepidophloios, 

 equally one cannot say it is a Lepidodendron. 



The figures given by Feistmantel and Dr. Macfarlane are conclusively 

 affirmative that at least some Halonia specimens belong to Lepidophloios, 

 whereas we have no example which shows in an undoubted manner that any 

 Halonia fossil can be referred to Lepidodendron, My own opinion is that 

 Halonia is exclusively related to Lepidophloios as its fruiting branch. Of 

 course, those authors who place Lepidophloios laricinus, Sternberg, in Lepido- 

 dendron, may consistently say that Halonia is the fruiting branch of Lepido- 

 dendron, but I am not aware that any recent writer has followed this classifi- 

 cation. 



Lepidophloios and Lepidodendron I regard as essentially distinct genera. 

 Lomatophloios is now united with Lepidophloios, hence I understand 



* See Renault, Cours d. Bot. Foss. p. 53, 1882. 

 t Geol. Mag. vol. x. April, 1873. 

 J Phil Trans. 1883, clxxiy. p. 459. 

 Z. c. p. 469. 



