ON THE STRUCTURE AND AFFINITIES OF METACLEPSYDROPSIS DUPLEX. 189 
Fig. 18. Transverse section of mature petiole-trace showing a large island (/s) of parenchyma at one end 
and an open groove at the other. w=waist; b=pinna-trace-bar; y=groove; prx=protoxylem group ; 
is=island of parenchyma; ¢=shallow depression—the last vestige of the groove. Slide 1155. x17. 
Fig. 19. Section similar to fig. 18. Pinna-trace-bar just detached from petiole-trace. Waist not so well 
marked as in last two figures. Lettering as before. Shde 1151. x 17. 
Fig. 20. Example of a petiole-trace with waist still less marked than in fig. 19. At the top an early 
stage in the development of the pinna-trace-bar is shown. Lettering as before. Slide 1i67 = x 17. 
Fig. 21. Transverse section of petiole-trace in which the waist is scarcely developed at all. A pinna- 
trace-bar is shown attached to the petiole-trace at the top of the figure. Pra’,, prx’,, pray, pra, = proto- 
“xylem groups on petiole-trace ; pra, pray, pra, prx,=protoxylem groups on pinna-trace-bar ; is=island of 
parenchyma; b=pinna-trace-bar. Slide 1171. x17. 
Fig. 22. Section of a petiole-trace from which all indication of a waist has vanished. Lettering as in 
other figures. Slide 1152. x17. 
Fig. 23. In the petiole-trace of this figure a further reduction to an elliptical trace is clearly seen. The 
pinna-trace-bar (b) is a much reduced one, and the pinna-traces do not pass beyond the cortex of the 
petiole, i.e. they are reduced. Slide 1264. x 16:5. 
Fig. 24. Transverse section of petiole-trace showing distinct elliptical form. Pinna-traces in this case 
also are reduced. The outer cortex (0.c) has no sclerotic layer, Slide 1194. x 18. 
Fig. 25. Rather oblique transverse section of a reduced petiole-trace. Pinna-trace-bar (b) does not 
‘divide into two pinna-traces. Slide 1189. x 15. 
j Fig. 26. Another oblique transverse section of petiole-trace. Pinna-trace-bar shows a double curve, but 
it does not divide into two to supply two pinne. Slide 1204. x 15. 
Prate III. 
Metaclepsydropsis duplex, 
Fig. 27. Transverse section of petiole-trace. Fig. 26 shows this same trace at a higher level. Slide 
x 15. 
Fig. 28. Transverse section of petiole-trace similar to that of fig. 27. Slide 1184. x 15. 
Fig. 29. Transverse section of another closely similar petiole-trace. pra =protoxylem groups ; g = groove. 
Slide 1189. x 17. 
__ Fig. 30. Transverse section of petiole-trace similar to that of tig. 29. It is inserted to show resemblance 
at this level of the traces of Metaclepsydropsis and Dinewron. Slide 1180. x 16°5. 
_ Fig. 31. Transverse section of petiole with trace slightly flattened. The outer cortex contains very 
little sclerenchyma, if any. Slide 1252. x 16-5. 
Fig. 32. Furthest-out section of a series showing the connection between petiole-trace and stem xylem. 
Slide 1242. x 15°5. 
__ Fig. 33. Section below that shown in fig. 30. The interval between is about } inch. pra, prx = proto- 
xylem groups ; 7s=island of parenchyma ; st=xylem of stem. Slide 1240. x 15-5. 
Fig. 34. Section some distance below that of fig. 31. Petiole-trace crushed against stem. Two sections 
w this the two unite, but are very much crushed at that level. Slide 1233. x 15°. 
Fig. 35. Transverse section of petiole to show the arrangement of the tissues. The sclerotic outer zone 
1e cortex is very distinct. The petiole-trace is shown more highly magnified in Pl. II. fig. 21. pet. tr= 
petiole-trace ; 7s!, is?=islands of parenchyma; sc.o.c=sclerotic outer cortex ; 0.c=parenchymatous outer 
cortex. Slide 1171. x83. 
Fig. 36. Transverse section of petiole-trace at a high level in the petiole. Slide 1140. x 17. 
Fig. 37. Transverse section of petiole-trace and combined pinna- and aphlebia-traces. 7s =island of 
arenchyma ; a@!, at=combined pinna- and aphlebia-traces ; pra =protoxylem groups. Slide 1248. x 19. 
Fig. 38. Transverse section above that of fig. 37. The combined traces show signs of a division into two ; 
the larger (upper) trace is the pinna-trace; pin. tr=pinna-trace; aph. tr =aphlebia-trace ; prx=proto- 
‘xylems. Slide 1244. x19, 
