GENERA OF BOTRYOPTERIS GROUP 333 



4. Other Genera. — With Botryopteris we may compare 

 another plant often found in the petrifactions of the 

 English Lower Coal-measures, the Rachiopteris cylindrica 

 of Williamson. 1 This has a slender stem, frequently 

 branching by dichotomy, and occasionally bearing the 

 bases of leaves. The preservation is often perfect ; the 

 stele resembles that of a small Botryopteris, but has a 

 very well-marked central protoxylem-group. The leaf- 

 trace bundles also bear some re- 

 semblance to those of Botryopteris, 

 and the associated petioles are of 

 a very similar type, i.e. the nearly 

 straight bundle has the proto- 

 xylem- points all on the same 

 side. The habit of the plant, with 

 its long slender stem and, as it 

 appears, very scattered leaves, Fig. 125.— Botryopteris. s P or- 



angium in transverse section, 



must have been widely different showing the muitiseriate an- 



r .1 r , 1 t-» ■ * ■ 1 nulus, and containing some 



from that of other Botryoptendeae, spores . Associated with B , 

 and, though it has been proposed ""'"^ x R a ^ ut IO °- s - 

 to include the species under Botry- 

 opteris, it may be preferable to found a new genus for it. 

 Another genus closely allied to Botryopteris, and 

 perhaps forming the simplest type of the family, is 

 Renault's Grammatopteris, founded on a species, G. 

 Rigollotif from the Permo- Carboniferous of Autun. 

 The habit represents the opposite extreme to that of 



1 "Organisation of Fossil Plants of Coal-measures," Part ix. Phil. 

 Trans. Roy. Soc. Part ii. 1878, p. 350, Figs. 80-87. Figs- 80, 86, and 

 87 are of the stem ; the smaller sections appear to be of roots. For a more 

 modern account see T. Hick, "On Rachiopteris cylindrica" Mem. and 

 Proc. Manchester Lit. and Phil. Soc. vol. xli. 1896. 



2 Flore fossile d' Autun et d'Epinac, p. 45, Plate xxx. Figs. 9-1 1, Plate 

 xxxi. Fig. 1. 



