Botryopteris ctntiqua , Kids ton. 1057 
Fig. 19 shows in the upper part of the photograph evidence of the stem having recently 
borne a large trace which has perished. Slides 402. 35 and 34. x 20. 
Fig. 19 a is a high-power micrograph of the stem stele from Fig. 19. It shows the details 
of the aphlebia trace which is destined to go off almost simultaneously with the monarch petiolar 
trace just given off. Slide 402. 35. x 95. 
Fig. 21. A low-power micrograph of a stem stele ( s.s .) showing simultaneously a diarch 
leaf-trace ( d.U .), a monarch leaf-trace ( m.l.t .), and an aphlebia trace (aph.'). Slide 417. 15. x 11. 
Fig. 22. A longitudinal section of the tracheides of a well-developed stem stele in a root¬ 
bearing region. They are reticulate and show various intermediate conditions between the porose 
marking met with in the metaxylem of the leaf-trace and the spiro-scalariform marking of the 
protoxylem elements. Slide 302. 19. x 95. 
Fig. 23. A transverse section of the petiole which may be seen leaving the stem on the left 
of Figs. 4 a and 5. The vascular bundle gives off a small group of tracheides which later become 
flattened out and do not leave the rachis (vide text, where it is suggested they represent an abortive 
aphlebia trace). Slide 407. 7. x 20. 
Fig. 24. A transverse section of a diarch petiole showing an early phase of branching. 
The pinna-trace separates off in the next section and eventually supplies a branch. Slide 390. 12. 
x 20. 
Fig. 25. A transverse section of one bundle ot a node of Protocalamites showing in the 
upper centripetal part pseudo-secondary thickening. Slide 306. 7. x 95. 
