Manchester Memoirs Vol. xliii. (1899), No. ^. 3 



in the manner typical of the aerial roots of this genus, 

 probably running parallel down the stem. Unfortunately 

 the stem to which my specimen belonged has not been 

 found. One of my preparations passes through twenty- 

 five roots or portions of roots ; not all of these show 

 secondary thickening, and it is noticeable that those with 

 secondary increase of tissue lie towards one side of the 

 section, but, from the absence of the stem, it is impossible 

 to say whether these are nearer the stem or further from it. 



In size, one can see that the roots showing secondary 

 growth are thicker in diameter than those showing only 

 primary wood, and this increased thickness applies not 

 only to the size of the central cylinder, but to the root as 

 a whole. The roots with secondary thickening are, as a 

 rule, also more irregular in outline ; this is, no doubt, due 

 to the difficulty of secondary growth in organs so closely 

 packed together as the roots of Psaronius. 



One of my sections, cut through about twenty roots 

 with primary structure only, shows that in this condition 

 they are specifically different from Psaronius renaiiltii. 



The roots of the latter fern possess five or six rays of 

 wood, generally five, while the roots of my new species 

 possess six, seven or even eight groups of primary xylem, 

 but are most frequently heptarch, i.e., possess seven groups 

 of primary tissue. In Fig. i, there are two roots with 

 primary wood only, one of them possessing seven, the 

 other eight rays of wood, each with a group of protoxylera 

 at its extreme outer end. In other respects these roots 

 agree very closely in their structure with those oi Psaronius 

 renaultii. The soft phloem masses are generally very 

 badly preserved, their place between the xylem rays being 

 often without any cellular tissue. Around the central 

 cylinder there are generally seen two well-preserved layers 

 of cells, separating the central cylinder from the cortex. 



