14 ANTONY GEPP AND ETHEL S. GEPP. 



EXPLANATION OF PLATES I— IV. 



PLAtE I. 



Lessonia grandifolia nob. Figs, la, lb. Mature fronds, showing flattened stipes dichotomously 

 branched and usually twisted, bearing long, simple, flat fronds with undulate margins and broken apex ; 

 tV natural size. Fig. 2. Three very young plants attached to a branch of Desmarestia harveijana, and 

 exhibiting even at this early stage almost as much branching as is found in a mature plant ; natural size. 

 Fig. 3a. Transverse section (diagrammatic, and showing no cell-structure) of stipes at base of fig. la, 

 showing concavo-convex form and rounded-obtuse margins ; natural size. Fig. 3&. Transverse section 

 of stipes, being the top of the cut branch on the left of fig. lb, and showing two acute margins and 

 a long, light-coloured intra-medullary band ; natural size. Fig. Sc. Portion of same (about two-thirds 

 of its width), showing that the intra-medullary band is composed of the cross-sections of scattered 

 trumpet-hyphse ; the bulk of the section consists of medulla, limited on the outside by the indistinct 

 subcortex and the pigmented cortical stratum, (x 10.) Fig. 4. The same in longitudinal section ; the 

 medulla here is also indicated by the trumpet-hyphse, which appear as longitudinal streaks, (x 10.) 



. PLATE II. 



Lessonia grandifolia (continued). Fig. 5a. Transverse section of mature lamina, representing one- 

 half only of its thickness, and showing on the left the short, vertical rows of pigmented cortical cells ; 

 beneath this is the subcortical stratum of about 2 rows of rotundate cells, which are twice as large as the 

 cortical cells and pass into the closely packed hyphas which form the outermost portion of the medulla 

 and appear here as round cells, but are shown to be hyphse in longitudinal section (compare fig. 7) ; 

 these hyaline hyphae become more and more separated towards the middle of the medulla, and run in 

 various directions through the gelatinoid matrix, and among them are shown a few ensheathed trumpet- 

 hyphas. (x 110.) Fig. bb. SmaU portion of similar section, showing four trumpet-hyphse with their 

 sheaths of small cells and a few of the ordinary hyaline hyphse of the medulla, (x 450.) Fig. 6. 

 Transverse section through a very young lamina (as in fig. 2), showing a monostromatic cortex of 

 granular coloured cells, a subcortical layer of 1-2 rows of large clear cells, and a medulla composed of a 

 few lax hyphse and one ensheathed trumpet-hypha. ( x 450.) Fig. 7. Longitudinal section of mature 

 lamina representing half the thickness of the frond, and showing (as in fig. 5a) the short vertical rows of 

 pigmented cortical cells ; the subcortex of 1-2 rows of rotundate cells twice as large as the cortical cells ; 

 and the medullary hyphse densely packed on the outer side and becoming gradually more laxly arranged 

 towards the interior, where, interspersed among them, are portions of three trumpet-hyphse in longitudinal 

 and one in transverse section, (x 110.) Fig. 8. Longitudinal section of very young frond, showing the 

 three strata already described for fig. 6. (x 340.) Fig. 9. Portion of medulla of stipes in longitudinal 

 section, showing a trumpet-hypha with its sheath of small cells and its wall densely marked with transverse 

 strise ; the cell-contents have contracted into a narrow strand along the axis of the cell, (x 450.) 



Lessonia simulans sp. nov. Fig. 10. Outer part of a longitudinal section of stipes, representing the 

 external part of the medulla, which is composed of densely packed straight hyphas ; these latter externally 

 pass gradually into a pluristromatic subcortex of large round and transversely oblong cells which, running 

 radially outwards towards the periphery, subdivide more and more, forming a cortex composed of short 

 vertical rows of small quadrate cells, (x 110.) 



. PLATE III. 



Desmarestia liarveijana nob. Fig. 11. Small portion of a large plant, showing that the ramification 

 is always opposite ; natural size. Fig. 12. Apex of an ultimate branchlet in surface view, showing that 

 the cortex is continued to the very apex of the axial filament, (x 110.) Fig. 13a. Transverse section 

 of a mature stem, showing its compressed form ; in the centre is the ensheathed primary axial filament and, 



