214 LEPIDODENDREAE. 



Halonia. As Halonia is on the whole of rare occurrence, only a few 

 authors have described it with any fulness. Carruthers's l account of it is 

 good and perspicuous, and is accompanied with abundant examination of 

 the literature. Halonia is very closely allied to Lepidophloios, so closely 

 that O. Feistmantel 2 desired to unite it at once with L. laricinus. Where 

 the covering of scale-like leaf-bases on the stem is preserved, which is not 

 often the case, it is said by authors to be of exactly the same character as 

 in Lepidophloios. Figures of stems in this condition will be found in O. 

 Feistmantel 3 , but the execution of them leaves much to be desired ; there 

 are similar figures also in Schimper 4 and Lesquereux 5 . Instead of four 

 rows of sunken scars we have here six to eight vertical lines of prominent 

 bluntly rounded protuberances, which are surrounded by leaf-bases and 

 show a rounded often depressed scar of separation on the apex only. 

 Mould-specimens, in which these scars are especially distinct, are the 

 foundation of Goldenberg's c account of Cyclocladia. Cyclocladia is some- 

 times found in the neighbourhood of Saarbriicken, and I have satisfied 

 myself of its identity with genuine Haloniae through the medium of a stem 

 found by myself in that locality and agreeing in every respect with the 

 figure. Casts without the outer rind are much more abundant. In this 

 form Cyclocladia occurs not unfrequently in the Millstone Grit of the 

 English Coal-measures. A fine specimen has been figured by Binney 7 , 

 and similar ones will be found in Brongniart 8 and in Lindley and Hutton 9 . 

 On these casts the traces of the foliar vascular bundles are seen only 

 in the form of the well-known small linear protuberances ; the scars of 

 separation on the apex of the protuberances may have a distinctly circular 

 outline and be depressed, but with a central raised bundle-trace-point ; 

 and when, as often happens, there is nothing more to be seen of the points 

 of emergence of the foliar bundles, the Haloniae have sometimes a wonder- 

 ful resemblance to the Stigmariae which will have to be considered later 

 on. Binney 10 has described pieces of stem of this kind, the connection 

 of which with Haloniae might appear doubtful where their anatomical 

 structure is not known. Such specimens gave rise to the view that 

 Haloniae must be the roots of Lepidodendreae, a view which we find in 

 older authors, Dawes n for example, and which was subsequently maintained 

 by Binney in spite of the discovery of more than one specimen showing 

 the leaves, and by Renault 12 also with certain limitations. The remaining 

 authors, Schimper 13 among them, consider that we are dealing in this case 

 with branches of lepidendroid growths, and that the protuberances repre- 



1 Carruthers (12). 2 O. Feistmantel (3). s O. Feistmantel (3), tt. 36, 37. 4 Schimper 



(1), t. 66. * Lesquereux (1), vols. i, ii, t. 87, f. I. * Goldenberg (1), t. 3, f. n. 7 Binney 

 (1), III, t. 18. * Brongniart (1), vol. ii, t. 28. Lindley and Hutton (1), vol. iii, t. 228. 



IU Binney (1), III, t. 16, f. i, and t. 17, f. i. ll Dawes (1). " Renault, vol. ii. 13 Schimper (1). 



