r>0 MR ROBERT KIDSTON ON 



on the other hand, with the Lepidodendron in the structure of the leaf-scars and the 

 anatomical details of the stem. 



M. Zeiller further points out what he believes to be another point of difference 

 between Sigillaria and Lepidodendron, viz., the stalked deciduous cones of Sigillaria, 

 and it must be admitted that, as far as we know, no Lepidodendron had stalked deciduous 

 cones ; but neither were all Sigillarian cones stalked, for in Sigillaria ( Ulodendron) 

 discophora, Konig, sp., and Sigillaria (Ulodendron) 'Faylori, Carr, sp., the cones have 

 evidently been sessile, and it was from the pressure of the bases of these deciduous 

 sessile cones on the bark that the cup-like depressions were made. But further, in these 

 the cones were borne in two vertical opposite rows, not in verticils, as in the 

 majority of Sigillaria}. 



Also in Lepidodendron Veltheimianum, Sternb., and Lepidodendron Landsburgii, 

 Kidston,* the fructification consisted of sessile deciduous cones, disposed likewise in two 

 opposite vertical rows, which produced the same cup-like depressions on the stem. The 

 case of deciduous cones is, however, very exceptional in Lepidodendron, whereas in 

 Sigillaria it seems to be the normal condition. In Lepidophloios, and probably in all 

 the species, we find the fructification in the form of deciduous stalked cones. The 

 most important distinction, however, between all these genera is the structure of the 

 sporangia, and in this Sigillaria and Lepidodendron are essentially distinct ; but the 

 other structural points in which they differ cannot, of course, be ignored in any system 

 of classification. 



On the other hand, it must be pointed out that there do not appear to be any 

 differences in regard to the internal organisation of the stems of Lepidodendron and 

 Sigillaria which would enable us to separate the stems of these two genera from each 

 other without the aid of additional characters. We may also place Lepidophloios in the 

 same category, for we now know as a fact that the stem the late Professor Williamson 

 described under the name of Lepidodendron fuliginosum is the stem of Lepidophloios 

 acerosus, L. and H., sp.t 



All these fossil Lycopods form a closely-connected group of genera, — Lepidodendron 

 and Lepidophloios pointing their affinities in the direction of Lycopodium and Selagin- 

 ella, and Sigillaria in the direction of Tsoetes, but each one differing in some important 

 respect from any recent genus. 



Sigillaria Sol., Kidston, n. sp. 



PL 111. fig. G. 



Description. — Stem ribbed, furrows straight. Leaf-scars occupying about half the 

 width of the ribs, sub-orbicular, lateral angles not prominent, upper margin slightly 

 notched, lower margin rounded. Vascular cicatrice punctiform, slightly above centre of 



* Trans. Roy. Soc. Edin., vol. xxxvii. p. 338, pi. iii. tigs. 9-10, 1893. 



t Lindley and Hutton, Foml Flora, vol. i., pi. vii. fig. 1, pi. viii. ( Lepidodencl/ron aceroswri). 



