502 



PTERIDOSPEEMS, ETC. 



[CH. 



of Vertebraria from India in which the longitudinal and trans- 

 verse grooves are occupied by a dark brown ferruginous substance 

 or by the carbonised remains of plant-tissues (fig. 338, C, D). 

 In transverse section, a Vertebraria cast appears to be divided 

 into a number of wedge-shaped segments radiating from a 

 common centre. Prof Zeiller' has figured specimens of Verte- 

 braria with portions of Glossopteris fronds still attached. 



Fig. 337. Vertebraria indica, Royle. Nat. size. (After Feistinantel.) 



The rhizome of Glossopteris, as represented by the Vertebraria 

 casts, is aptly compared by Zeiller^ with that of the recent 

 Polypodiaceous fern Onoclea struthiopteris. Sections of the 

 recent stem (fig. 338, E, F) show that the form is irregularly 

 stellate owing to the presence of prominent wings which 

 anastomose laterally at intervals as shown by the examination 

 of a series of sections. The leaf-traces ^ve derived from the 

 steles of adjacent wings. Fig. 338 (B and A) represents some- 

 1 Zeiller (96) A. 2 Zeiller (96) A. 



