Mr Kidston on British Carboniferous Lycopods. 01 



instructive specimens of our Carboniferous Lycopods, a frag- 

 ment of a large specimen of S. discophora, which was 

 unfortunately broken into several pieces, when removing it 

 from the roof of the Wliisller Seam, Kilmarnock. This 

 example shows clearly the central and two lateral cicatricules 

 of the leaf-scar. A small portion of the specimen is sliown 

 in ri. IV., figs. 1, la. This specimen conclusively proves 

 that the leaf-scars of S. discophora, Konig, sp. (= U. 

 minus, L. & H.), are provided with three cicatricules very 

 similar to those of Sigillaria, in which genus I believe 

 the plant under discussion should be placed. It is very 

 remarkable, that in such a common British Coal-measure 

 fossil the true outer surface of the bark, showing the leaf- 

 scars in a good state of preservation, is so seldom met with. 

 One reason for this is the persistence of tlie leaves, which 

 appear to have retained their attachment to the stem much 

 longer than in the other Coal-measure Lycopods, and it is 

 not uncommon to find the leaf-scars on stems of large 

 specimens of S. discophora entirely obliterated by the foliage 

 of the plant being closely adpressed to the bark. 



I united U. majus and U. minus, L. & H. ; but M. Zeiller 

 regards them as distinct species, and has since figured a 

 specimen which he believes to be the U. majus of Lindley 

 and Hutton,^ with which he unites aS^. {Lepidodendron) 

 discophora, Konig. From the examination of a plaster cast 

 of Konig's original specimen, which is still preserved in 

 the collection of the British ^luseum, I feel quite satisfied 

 that Konig's plant is beyond all doubt referable to U. minus, 

 L. & H., and not to their U. mccjus, whatever may be the 

 claims of U. mccjus, L. & H., to rank as a species. The 

 size of the ITlodendroid scars or of the leaf-scars is of no 

 specific value, and I have specimens of S. discophora in 

 my own collection with Ulodendroid scars ranging up to 

 5 J inches in their greater diameter. There is no L'loden- 

 droid scar on the specimen of U. majus figured by Zeiller ; 

 of course this does not prove that his specimen does not 

 belong to that species, but as the case stands, I at piresent 



^ "Flore fossile clu bassin liouiller de Valenciennes," p. 481, pi. Ixxiii., 

 fij;. 1. 



