168 W. T. GORDON 
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79 
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TextT-Fie, 2.—Metaclepsydropsis duplex, Series of transverse sections of petiole showing pinna departure and position 
of aphlebie, Natural size. After sections 1310-1318, Kidston Collection. 
Text-Fic. 3.—Formation and gradual reduction of islands of parenchyma in the petiole-trace. The series illustrates: (a) the 
formation of the island on the upper ends of the trace, and (b) the formation of the groove on the lower ends. The grooye — 
is seen dying out on the inner side of the island at the top of the traces. Complete series shown by figures in following 
order: 1, 2, 3, 4, 5, 6 (upper ends), 3, 4, 5, 6 (lower ends), 1, 2, 8, 4, 5, 6 (upper ends, inner side of island), 
15 2. 3. 4, 
Text-Fie. 4.—Diagram to illustrate distinction between ‘‘ arms” and mere dilatations of the arms or of the ends of the trace: 
(1) Dinewron ellipticum, x 45. (2) Metaclepsydropsis duplex, x 12. (8) Diplolabis rémeri, x 7. (4) Htapteris Scotti, x 14. 
A=arm ; D=dilatation, Slightly diagrammatic drawings from actual specimens. Magnification indicated after name, 
