848 MR JOHN M'LEAN THOMPSON ON 



Partial reunions are made between the adaxial strands at various points, but when 

 the lamina — which is decurrent on either side — is reached, the trace has again 

 three distinct bundles. To right and left finer veins depart from the adaxial bundles, 

 and as the lamina is ascended and the midrib thins out, the small abaxial strand 

 unites with one of its adaxial neighbours, and the trace is reduced to two strands, 

 one being larger than the other. Further on the larger strand divides, and when 

 one of the two bundles thus formed has united with the smaller strand, the trace is 

 again binary. Towards the end of the midrib the two strands fuse, and the small 

 single bundle thus formed dies away in the tip of the lamina. 



It may be worthy of note that while the course and nature of the small abaxial 

 strands has been so variable, nevertheless, throughout almost the entire course of 

 the leaf-supply, the large abaxial bundles have been conspicuously uniform in size, 

 form, and position, and it is not until the pinnae are reached that fluctuations appear 

 in them. Those fluctuations are, however, preparatory to the reductions necessary 

 in the lamina. As a point of comparison with Deparia pi^olifera, Hook, and 

 Grv. — which will be mentioned later, — it is to be noted that towards the base of 

 the rachis there are in that species only two large slanting bundles composing the 

 leaf-trace, and thus, at this level at least, its leaf-trace is on a simpler plan than that 

 of Deparia Moorei, Hook. 



The Lamina. 



In each section the margin of the developing lamina is usually seen to be occupied 

 by a wedge-shaped, marginal, initial cell, from the inclined inner surfaces of which 

 alternating segments arise, but occasionally in specially thin parts the marginal initial 

 is a two-sided cell from whose inner surface narrow parallel segments arise, and thus, 

 locally, the margin is of an almost filmy texture. At maturity the lamina is usually 

 thin, its mesophyll is well ventilated, stomata are numerous on both surfaces, and the 

 marginal cells form a narrow, firm border. Unbranched hairs are abundant on both 

 surfaces along the course of the larger veins and more scattered over the finer reti- 

 culations and general surfaces, and while the leaf is still unexpanded, curious branched 

 and unbranched glandular hairs are scattered over the lamina. It will be evident 

 (figs. 15-18) that these hairs are distinctly different from those found on the rachis. 



From the midrib of each pinna a fairly prominent vein runs to the tip of each 

 pinnule, and as it passes forward gives off, right and left, numerous delicate anasto- 

 mosing strands. Only here and there is this fine network directly connected with 

 the midrib of the pinna, and then only by single, narrow strands (fig. 12). I mention 

 this point so as to draw a comparison with the condition in Deparia prolifera, whose 

 pinnae have an open venation in which the central veins of the pinnules are alone 

 connected with the midrib of the pinna (fig. 11). In Deparia prolifera, in the 

 material examined, all the veins of each pinnule reach the leaf-margin, but in 

 Deparia Moorei only a limited number actually reach the margin, and many which 



