96 VEBTEBBABIA. 



of the rhizome, which in the fossil state are sometimes represented 

 by a small amount of carbonaceous material, while the transverse 

 grooves may be explained as the points of anastomosis of two of 

 the wings at short intervals. Zeiller also figures fronds attached 

 at the transverse grooves, and in other instances he finds a print 

 of the attachment of a leaf in a similar position. 



In 1897 Oldham 1 published an account of a specimen of Verte- 

 Iraria from India, to which a number of fronds, probably of 

 Glossopteris indica, were attached, thus confirming Zeiller's con- 

 clusion as to the nature of this fossil. At the same time Oldham 

 pointed out that his specimens of Vertebraria 2 did not agree in all 

 particulars with those described by Zeiller, and he doubted whether 

 the explanation of the morphological features of the fossil put 

 forward by that author was entirely correct. In particular, he 

 pointed out that in some of the Indian specimens, as seen in 

 transverse section, a shell of coaly matter, which was apparently 

 wanting in the South African specimens, was present outside the 

 wedge-like sectors. He concludes that Vertebraria must have been 

 a stem with a central axis connected with some outer tissues by 

 radiating, longitudinally disposed plates or septa, which were 

 usually eight in number, in addition to numerous transversely 

 placed septa, which divided up the lacunae between the longitudinal 

 septa into chambers. 



In 1902 Zeiller 3 replied to Oldham's criticism, and maintained 

 his explanation, pointing out that the small traces of a carbonaceous 

 layer outside the wedges, which are found in some specimens as seen 

 in transverse section, correspond with the points of anastomosis of 

 two wings of the rhizome. 



It must be admitted that Zeiller's explanation of Vertebraria is 

 the best which has so far been put forward. Yet, without 

 attempting to criticise it in detail, I am not entirely convinced 

 that the morphological features of that fossil are directly due to 

 the structure of the external surface of a rhizome. It must be 

 remembered that Etheridge, 4 in 1894, figured a specimen showing 

 some fronds of Glossopteris Browniana attached to an axis, which 



1 Oldham (97), pi. lii. 2 Oldham (97), pis. iv, v. 



3 Zeiller (02 1 ), p. 17. 



* Etheridge & David (94), p. 228, pi. xviii, fig. 1 ; pi. xix, figs. I, 2. 



