STAUROPTERIS 337 



recalling that of the Zygopteris petioles. The branches 

 are of many orders ; those of intermediate dimensions 

 have a three-armed xylem, while the excessively fine 

 terminal ramifications are traversed by a bundle of 

 correspondingly simple structure. Certain slender 

 strands which are given off concurrently with the 



Fig. 126. — Stauropteris oldhamia. Transverse section of vascular bundle of main 

 rachis, showing the cruciform xylem with protoxylem near the four angles. Groups of 

 large sieve-tubes are seen in the bays of the wood, and small-celled phloem between 

 wood and cortex. X 60. S. Coll. 2202. From Tansley, New Pliytologist. 



main branches are described by M. P. Bertrand as 

 supplying aphlebiae — another point of analogy with 

 Zygopteris. 



It was on the delicate ultimate branches of the rachis 

 that the terminal sporangia were borne (Fig. 127). 

 The fronds at present known appear to be all fertile ; 

 whether other vegetative leaves also occurred, or the 

 foliage was of an extreme xerophytic type, with the 



