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Transactions. 



had previously been separated by some writers as two species — viz., as 

 T. tannensis and T. lanceolata. She gives figures of the aerial stems of 

 these two forms. In the section in the present paper which deals with 

 " Occurrence and Habit " I noted the fact of these two forms, and indicated 

 that the prothalli and young plants which I had obtained belonged to 

 the form which grew to the greater size and had the more pendulous and 

 flaccid habit and possessed the larger leaves. This is the form referred 

 to by Miss Sykes as T. lanceolata. Cheeseman (1906) does not recognize 

 more than the one species in New Zealand, to which he gives the general 

 name T. tannensis, although in a note he adds, " By some authors it is 

 split up into three or four, distinguished mainly by the shape of the apex 



Fig 73. — Complete young plant, showing parent prothallus, foot, lateral bud, and also 



both ends of rhizome developed into aerial stems. X 2. 

 Fig. 73a. — Apex of smaller aerial stem shown in fig. 73. X 9. 

 Fig. 74. — Apex of a young aerial stem, showing initiation of leaf-formation. X 9. 

 Fig. 75. — Apex of rhizome of young plant, showing dichotomy. X 10. 



of the leaf (which I find to be variable even in the same individual) and by 

 certain histological details, the constancy of which has yet to be established." 

 I have not had access to the papers referred to by both Miss Sykes and 

 Mr. Cheeseman as setting forth the exact morphological and histological 

 details on which the distinction is drawn between the different forms of 

 Tmesipteris, so cannot refer particularly to them. However, I shall be 

 noting in this section of my paper certain details in the stem-structure 

 of the two forms referred to above. 



Having an abundance of young plants of Tmesipteris of the form 

 T. lanceolata of all stages of growth, I made a study of the development 

 of the vascular cylinder of both the rhizome and the aerial shoot. I have 

 no serial sections of the youngest plantlets, such as those shown in figs. 64 



