xxv] 



ANKYROPTERIS 



453 



internally of parenchyma which becomes thicker- walled towards 

 the periphery and bears multicellular epidermal hairs. A leaf- 

 trace is detached in the form of a triangular strand and is 

 formed by the tangential extension of the distal end of an arm 

 of the stele. The trace, on its way through the cortex, divides 

 into two ; the outer branch gradually changes from a slightly 

 curved band to an H -shaped meristele; the inner branch, 

 which supplied an axillary shoot, is similar to the stele of the 



B 



Fig. 312. A. 



B. 

 C. 



Thamnopteris Schlechtendalii. Leaf- trace: px, protoxylem; 



«, island of parenchyma. (After Kidston and Gwynne- 



Vaughan.) 

 Ankyropteris corrugata. Single trachea with tyloses. 

 A. bibractensis. Part of foliar strand. (After P. Bertrand.) 



stem, but smaller. Scott ^ has recently recorded the occurrence 

 of scale-leaves (aphlebiae) in this species like those described by 

 Stenzel in A. scandens. 



Bertrand includes in Ankyropteris Renault's species Zy- 

 gopteris bibractensis'' and Williamson's species Rachiopteris 

 corrugata^: the former he names A. bibractensis var. west- 



1 Scott (07) p. 180. 



3 Williamson (77) Pis. v.— vii. 



2 Eenault (69) ; Williamson (74) A. p. 697. 



