284 PTERIDOPHYTA. [CH. 



recognised the generic identity of Goppert's fragments with 

 the Indian and Australian stems referred to the genus Phyllo- 

 theca by McCoy' and Bunbury". 



We may define the species as follows : — 



Stem reaching a diameter of 2 — 3 cm. with internodes as 

 much as 4 cm. long, the surface of which is traversed by 

 longitudinal ridges and grooves which are continuous and not 

 alternate at the nodes. Branches arise in verticils from the 

 nodes. The leaves have the form of funnel-shaped sheaths split 

 up into narrow and spreading linear segments, each of which is 

 traversed by a median vein. The fertile shoot terminates in 

 a loose strobilus bearing alternating whorls of sterile bracts and 

 sporangiophores. 



The specimens on which this diagnosis is founded are for 

 the most part fragments of sterile branches. Some of these 

 present the appearance of Calamitean stems in which the 

 ridges and grooves continue in straight lines from one inter- 

 node to the next. Similar stem-casts have been referred by 

 some writers to the allied genus Schizoneura, and it would 

 appear to be a hopeless task to decide with certainty under 

 which generic designation such specimens should be described. 

 The portion of stem shown in fig. 67 affords an example of 

 an Equisetaceous plant, probably in the form of a cast of a 

 hollow pith, which might be referred to either Phyllotheca or 

 Schizoneura. The specimen was found in certain South 

 African rocks which are probably of Permo-Carboniferous age'. 

 It agrees closely with some stems from India described by 

 Feistmantel^ as Schizoneura gondwanensis, and it also resembles 

 equally closely the Australian specimens referred by Feist- 

 manteP to Phyllotheca australis and some stems of Phyllotheca 

 indica figured by Bunbury". 



The longitudinal ridges and grooves shown in fig. 67 

 probably represent the broad medullary rays and the pro- 

 jecting wedges of secondary wood surrounding a large hollow 



' McCoy (47) PI. xi. fig. 7. ' Bunbury (61) PI. xi. fig. 1. 



■^ Seward (97^) p. 324, PI. xxiv. fig. 1. 



^ Feistmantel (81) PI. ix. A. fig. 7, &c. 



=■ ibid. (90) PI. XIV. fig. 5. « Bunbury (61) PI. xi. fig. 1. 



