IX] 



PHYLLOTHECA. 



285 



pith, as in Galamites. In the Calamitean casts the ridges and 

 grooves of each internode usually alternate in position with 

 those of the next, as in Equisetum (fig. 54, A), but in Phyl- 

 lotheca, Schizoneura and Archaeocalmnites there is no such 

 regular alternation at the nodes of the internodal vascular 

 strands. 



!^ 



i 



m 



Fig. 67. Phyllotheca I '^ nat. size. From a South African specimen of 

 Permo-Carboniferous age in the British Museum. 



In Phyllotheca and ScJdzorieura there are no casts of ' infra- 

 nodal canals ' below each nodal line, but these are by no means 

 always found in true Calamites. It is therefore practically 

 impossible to determine the generic position of such fossils as 

 that shown in fig. 67 without further evidence than is affoitled 

 by leafiess casts. 



A few examples of Phyllotheca deliqtcescetui have been 



