3 o8 STUDIES IN FOSSIL BOTANY 



wood, as shown in successive transverse sections, it 

 follows that the angle of divergence between two 

 successive leaves was in this case j? (Fig. 116, I-S)- 

 A short xylem-arm from which the leaf-trace has just 

 separated appears merely as a slight bulge (Fig. i 16, i) ; 



-ax. 



Fin. 115 — Zygojttcris Grayi. Transverse section of stem, with axillary shoot and part 

 of petiole. In the middle of the stent the five-angled stele is seen (cf. Fig. 116). /. t. , 

 leaf-trace, about to give off the axillary strand ; .v./., " scale -leaf" ; ax. , axillary shoot 

 of next node below ; pet., part of petiole of the subtending leaf. The small strand in 

 the cortex to the right belongs to a scale-leaf. X about 4. From a photograph by 

 Mr. L. A. Boodle. Will. Coll. iqiq A. 



those of successively greater length assume a truncated 

 form at the end (Fig. 116, 2, 3, and 4); while the 

 longest arms of all spread out laterally, so as to be 

 broadest at their termination, acquiring a bicornute out- 

 line (Fig. 116, 5). It is the enlarged end of the arm 

 which, at a somewhat higher level, becomes detached, to 



