554 MR ROBERT KIDSTON ON 



Structure of the Leaf- Cushion. 



I reproduce on PL I. fig. 11a leaf-cushion of Lepidophloios crassicaule, as given by 

 Stur.,* on which he shows the ligule-scar (a) and the vascular glands (c) on each side 

 of the medial line, similarly to what occurs in Lepidodendron. In respect to this figure, 

 which, he says, is a cushion on a specimen of Lepidophloios crassicaule, Corda, in the 

 Prague Museum, I can only say that I have never seen these structures, as represented 

 by Dr Stur, on any of the very many specimens of Lepidophloios which I have examined, 

 nor am I aware that any other writer on Lepidophloios has been more fortunate than 

 myself. I am, therefore, forced to conclude that there is some error in Dr Stur's 

 observation, for, were it otherwise, surely it would have met with corroboration. It is 

 on this evidence that Stur treats Lepidophloios as a condition of Lepidodendron. t 



At PI. II. fig. 9, I give a leaf-cushion of Lepidophloios acerosus, L. and H., sp., from 

 the Lower Coal Measures, Tullygarth, Clackmannanshire. This specimen shows imme- 

 diately beneath the leaf-scar, and terminating the medial keel, a small tubercle, \ in 

 which is placed a small sub-triangular pit. I have never observed any other scar or 

 cicatrice (other than this and the leaf-scar) on the cushions of Lepidophloios, and I have 

 no doubt that, morphologically, this small tubercle corresponds to the two small oval pits 

 seen on the cheeks of the leaf-cushion of many species of Lepidodendron. They are 

 situated one on each side of the medial line, immediately beneath the leaf-scar, but from 

 some species of Lepidodendron these two small pits beneath the leaf-scar are constantly 

 absent. In Lepidophloios Scoticus no tubercle beneath the leaf-scar has yet been 

 observed on any of the many specimens I have examined. 



From what has now been stated, I think it must be conceded that Lepidophloios 

 forms a well-marked genus, essentially distinct from Lepidodendron, but with which 

 Lomatophloios must be united, and whose fruit-bearing branches are the well known 

 Halonia L. and H. 



British Species of the Genus Lepidophloios. 



Lepidophloios, Sternberg, 1826. 



1826. Lepidophloios, Sternb. Ess. flore monde prim., vol. i. fasc. 4, p. xiii. 

 1833. Halonia, L. and H. Fossil Flora, vol. ii. p. 14. 



* Culm. Flora d. Ostrauer u. Waldcnburger Schichten, pi. xix. (xxxvi.) fig. 26. 



t For the purpose of comparison, I give a figure of a Lej>idodendroid cushion and leaf-scar copied from Stur (loc. 

 cit.), pi. xix. fig. 1. Stur describes it as follows : — rb, rhomboidal leaf-scar ; b.g., the three points of the leaf vascular 

 bundles ; I, the ligule-scar (" Ligulagrube") ; s, point of insertion of the sporangium ; m, medial line of leaf-cushion ; " . 

 the line of the field (" Wangenlinie " of Stur) ; b.p.g., vascular pits of the cushion (" Gefassedrusen des Blattpolsters "). 



The reasons have already been given for the rejection of the terms "ligule-scar" and "point of attachment of the 

 sporangium." Of the three cicatricules within the leaf-scar, the two lateral — the parichnos of Hovelacque— are 

 probably glandular ; the two little pits beneath the leaf-scar, one on each side of the medial line, are also apparently 

 glandular in function, and have no connection with the vascular system. 



J This tubercle is not always present, but the majority of specimens possess it. 



