46 president's address. 



Plate iii. 



Fif. 1. — Upper portion of a leaf of Caesalphiia Gilliesii to show th; terminal 

 pinna present in this species. This, in the Acacias, aborts, and is represented by 

 a remnant, the terminal seta. 



Fig. 2. — Leaf of a seedling of A. discolor, showing the basipetal. incomplete 

 developments of the leaflets of the middle pair. 



Figs 3-6. — Leaves of Reversion-shoots of .,•/. iutf<texa (?). 



Fig. 3. — Back view of a leaf with what appears to be a terminal pinna. The 

 middle one and the one on the right constitute the apical pair, as indicated by the 

 presence of the terminal seta (discernible with a lens in the photo>. The one 

 on the left, whose fellow did not develop, represents an incomplete second pair 

 next below, very close to the apical pair because the internode did not lengthen. 



Fig. 4. — Leaf with one pinna of the second pair missing. Two alternate, or 

 perhaps odd pinnae below, represented by large leaflets. 



Fig. .5. — Leaf with the apical pair of pinnae only, and a terminal pinna repre- 

 sented by a leafiless thread-like axis, and a terminal seta. The whole of the axis 

 is more or less flattened. 



Fig. 6. — Another leaf with three pairs of good pinnae, and a rudimentary, leaf- 

 less, terminal pinna, and a terminal seta. Some flattening of the axis throughout, 

 but retarded where the pinnas are. 



Plate iv. 



Fig. 1. — Complete leaf (back view) of A. Baileyaiia, with four pairs of pinnae, 

 and a terminal seta, visible with a lens. Note the excessively short petiole. 



Figs. 2. — Leaves of reversion-shoots of A. implexa, including two complete 

 euphyllodes. The branchlet shows the order of the succession. Xote the inversely 

 proportional ratio in which the two antagonists are present — good pinnae on the 

 upper part of the axis: much flattening on the lower part, extending upwards, but 

 retarded where the pinna are (especially in Fig. 31. Also the termmal seta at the 

 tip of the larger phyllode : rudimentary pinnae in the smaller one. 



Plate V — Leaves of Reversion-shoots of A. iviplexa (?). 



Figs. 1-5. — Most interesting stages of the contest when the antagonists are fairly 

 equally matched. Good pinnae on the upper part of the axis: flattening most 

 marked on the lower part, extending upwards, but retarded where the pinnae are. 

 Note the terminal setae, with some indication of the developing pinnae of the apical 

 pair in the youngest euphyllodes, and the terminal seta alone in the largest one. 



Plate vi — Leaves of Reversion-shoots of A. implexa (?). 



Figs. 5-6 supplement the series shown in Plate v., and are fine specimens. 



Figs. 1-3. with 11 and 10 pairs of pinnae, the maximum number, as yet seen, 

 show the pinnae doing their very best. Some of the lowest pinnae show reduction 

 in the number of leaflets. The lowest pinnae in all three are represented by leaflets. 

 The presence of so many pinnae has obviously put the brake on the flattening of 

 the axes. Note the short petiole in Fig. 3. and the terminal seta in Fig. 5. Also, 

 that, in the leaves of this species, the pinnae are attached to the midrib, and not 

 to the margin, as in A. suaveoletis (PI. i.). 



Plate vii. — Leaves of Reversion-shoots of A. implexa (?). 



Figs. 1-7.— Six decadent stages of the waning pinnae, variou.sly located, and a 

 complete euphyllode. The common petioles or primary leaf-axes show more or less 

 flattening from base to apex. TTie distal portion of No. 4 is missing: but note 

 the retardation of the flattening in the lower portion of this and No. 6. where the 

 reduced pinnae, or leaflets are: and how the flattening increases distad of the 

 distal pinna or pair of" them. Note also the short petiolar portion of No. 6. in which 

 the two proximal pairs of pinnae are represented by leaflets. 



