50 L. COCKAYNE 



The living Osmundaceae, thanks to the brilliant work of Kid- 

 ston and Gwynne-Vaughan, 2 stand out, at the present time, a 

 conspicuous "link with the past," to use Professor Seward's 

 apt term. 3 New Zealand can boast noteworthy representatives 

 of both living and extinct genera, while the former grow under 

 absolutely virgin surroundings, a matter of much moment when 

 considering ancient geological climates and life conditions. 



The living New Zealand genera Todaea and Leptopteris, though 

 united by many pteridologists, belong to ecologically distinct 

 classes, while systematically the former possesses large sori of 

 many sporangia, and the latter small sori of few sporangia. Thus 

 limited, Todaea consists merely of the one species T. barbata (L.) 

 Moore. This fern is noteworthy, first of all, through its striking 

 discontinuous distribution (South Africa, Eastern Australia, Tas- 

 mania, and New Zealand), a fact which can be most reasonably 

 explained, as Christ 4 and Seward 5 both agree, on the supposi- 

 tion that it must have been at one time more widely spread in 

 the southern circumpolar region. Further, in New Zealand it is 

 restricted to the extreme north, hardly extending beyond lati- 

 tude 35° 20' south, 6 although it can certainly live quite well south 

 of that limit so far as climatic and edaphic conditions go. In fact 

 it is in the position of a species disappearing before our very eyes, 

 for a slight increase in the number of rainy days, or a general sink- 

 ing of the land surface would cause its gradual extinction. Nor 

 is such a happening at all unlikely, since the extreme north of 

 Auckland has undergone many changes in level, and vast kauri 

 (Agathis australis) forests, as evidenced by extensive deposits of 

 fossil resin, occupied land now dune, heath, swamp, and bog. 7 



2 Gwynne-Vaughan, D. T., On the fossil Osmundaceae. Trans. Roy.Soc. Edinb.> 

 45, 46 and 47, 1907-1910. 



3 Seward, A. C, Links with the past in the plant world, Cambridge, 1911. 



4 Christ, H. , Die Geographie der Fame, p. 154. Jena, 1910. 

 & Op. cit., p. 78. 



6 Christ has unfortunately confused Auckland, the geographical district of the 

 North Island of New Zealand, where T. barbata occurs, with Auckland Island, 

 one of the New Zealand Subantarctic Islands in latitude 50° 20' south, an easy 

 enough mistake, though he is quite right in assigning another tree-fern, Hemitelia 

 Smithii, to that bleak and wind-swept spot (op. cit., pp. 246, 247). 



7 Cheeseman, T. F., Trans. N. Z. Inst., 29: 337, 1897; Bell, J. M. and Clarke, E. 

 deC, Ibid., 42: 614-615, 1910. 



