84 PTERIDOSPERMEAE [CH. 



bears a close resemblance to H. tiliaeoides. Heterangium punctatum 

 Ken. and H. Renaulti 1 (Brongn.) also from the Permian of France 

 were originally placed in the genus Lycopodium and afterwards 

 recognised as stems of Heterangium. A fourth French Permian 

 species, H. bibractense 2 , is peculiar in the possession of a very 

 small primary stele encircled by deep wedges of secondary xylem,. 

 but without more information it is impossible to speak with 

 confidence as to its systematic position. Kubart 3 has recently 

 published brief descriptions of some stems from the Ostrauer 

 coal-basin in Moravia all of which he regards as specifically distinct 

 from the English types. In Heterangium Sturi the primary xylem 

 is almost exarch and the peripheral xylem groups are not very 

 clearly defined : in H. alatum, so called from the presence of lateral 

 wings on the petioles, the leaf-trace strands are more sharply 

 differentiated from the rest of the stele. H. polystichum is a 

 similar type, and H. Andrei, with a relatively larger amount 

 of parenchyma in the stele and thicker stems forms an additional 

 link between Heterangium and Lyginopteris*. Prof. Johnson 5 has 

 described a species of Heterangium, H. Tiibernicum, from Upper 

 Devonian and Lower Carboniferous beds in Co. Cork, Ireland, based 

 on some impressions of frond fragments without any pinnules. The 

 occurrence of numerous transverse striae on the rachis and lateral 

 branches suggests comparison with Heterangium fronds, but an ex- 

 amination of the specimens led me to suspect that some at least of 

 the striae are cracks and not original features. The presence of 

 spur-like appendages from the lower surface of the pinnae near their 

 origin from the rachis is recorded as a peculiar character, and some 

 obscure oval bodies, the nature of which is extremely doubtful, 

 are considered to be seeds. The imperfection of the material 

 hardly justifies the institution of a new species of Heterangium. 

 Heterangium ranges from the Lower Carboniferous to the 

 Permian strata and is thus older than Lyginopteris which in the 

 form of petrified stems is not recorded from the Lower beds of 

 the Carboniferous system. Heterangium has been described as 



1 Renault (96) A. pp. 253, 255. 2 Ibid. p. 252, PI. LXV. figs. 3, 6. 



3 Kubart (14). 



4 Dr Scott who has seen sections of this species tells me that it is a striking 

 intermediate form. 



5 Johnson (12). 



