636 MR JOHN M'LEAN THOMPSON ON 



whether or not there are other characters which will justify their separation. And 

 finally, a brief consideration of the facts above detailed regarding Platyzoma will 

 suffice to show that the Grleicheniaceous affinity has not been proved, and that, 

 even supposing Platyzoma be admitted to this group, its nearer relationships are in 

 much doubt. 



In this paper are set forth some additional facts gleaned from the specimen 

 supplied to us from Sydney Herbarium. It is still impossible to speak with assur- 

 ance of the affinity of Platyzoma, but the facts here detailed may serve as a basis 

 for comparisons at a later date, when the development of the sporangium will 

 be described. 



The axis is a slender, horizontal rhizome measuring some 2|- inches in length 

 (fig. 6). It is closely invested by a dense covering of beautiful golden-brown un- 

 branched hairs (figs. 2 and 8), which spring from all sides and cluster around the 

 leaf-bases. The roots are inserted on the lower surface and occasionally on the sides 

 of the rhizome. They are strong and fibrous and are frecp^ently branched. The root 

 hairs are remarkably long and persistent, and their walls are thick and brown. The 

 heterophylly is well shown. The large pinnate leaves are about 11 inches long, 

 while the small filiform leaves vary from about 2 1- inches to ^ inch in length. The 

 petiole of the pinnate leaves measures about 1 inch. The leaves are closely crowded 

 upon the condensed and apparently slow-growing rhizome, and are definitely zoned, 

 so that, if the leaves of a single year's growth be examined, they are found to divide 

 roughly into two groups. Of these the first are composed almost exclusively of long 

 pinnate leaves, the second of delicate filiform types. At first sight it might be con- 

 cluded that the pinnate leaves definitely precede the filiform leaves in order of 

 development. Further, the majority of the pinnate leaves spring directly from the 

 upper surface of the rhizome, and only a few encroach slightly upon its sides. No 

 pinnate leaves arise from the lower surface of the stem. The filiform leaves are in- 

 serted upon the sides and lower surface of the rhizome, and, curving forwards and 

 upwards, pass out in a fairly definite group in front of the pinnate leaves. There 

 might be a slight tendency towards a succession from pinnate to filiform leaves in a 

 season's growth, but this is not the chief cause of the zoning. It is due primarily to 

 a definite tendency in this rhizomatous plant to initiate the larger leaves on or 

 towards the upper surface, and the smaller leaves upon the sides and lower surface. 



The length of the pinnate leaves varies from about 10 inches to 12 inches. They 

 are either sterile or fertile, but stature is of little value as a guide to their sterility 

 or fertility. The filiform leaves are invariably sterile. The pinnate leaf is typically 

 unbranched, but, as has already been noted, a dichotomous branching may occur. 

 Only slight differences exist between the pinnae of sterile and fertile leaves, and, 

 further, a leaf may be partly fertile and partly sterile. The fertile pinnae are, if any- 

 thing, more robust than the sterile pinnae, and their margins are strongly revolute 

 (compare text-figs. 1 to 5 and 9). The vascular supply is in both cases a sympodium 



