284 C. SKOTTSBERG 



the genus as Antarctic in origin. But, CorELAND remarks, if the ferns as a group 

 were of tropical origin the\- would be expected to be far more abundant north- 

 ward, where the land areas increase, than southward where the land decreases 

 — and very much so — in size, and this would be still more so if they were of 

 northern origin. The conclusion is that if a family or genus is mainly southern 

 to da\', this fact is a strong indication of its Antarctic origin and that, if the pre- 

 sent range is wholl}' southern, the evidence becomes almost conclusive. If the 

 more primitive families or genera are found to be characteristically southern, a 

 southern seat of old fern evolution is almost demonstrated [68. 626). But when it 

 comes to the large families, their history may be much more difficult to read: 



A large family, even if of southern origin, cannot possibly be predominantly southern 

 in i)resent distribution, because tropical and northern species must outnumber the whole 

 tlora of Antarctic America, or even of New Zealand {6y . 158). 



With this he wants so sa}% I suppose, that a vigorous family has invaded the 

 tr()j)ics and also extended north under rapid evolution of genera and species con- 

 cealing the j)rimary origin; he believes this evolution to have been so rapid that 

 the j)eriod since the Miocene has been sufficient to create most of the existing 

 species and a large part of the genera and for their spread over any expanse ot 

 suitable land area (I.e.). 



We have no evidence that the Tropics as a whole were at any past time unfit for ferns; 

 and the assumi)tion that this has been the chief place of evolution obviates the neces- 

 sity of assuming and explaining migration in latitude. It is only w-hen we open our 

 eyes to anomalies in present distribution that appeal to other places of evolution be- 

 ( omcs necessary [6y. 163). 



(ireat geographical disjunctions, of which the Juan Fernandez fern flora offers 

 man\- examples, are such anomalies, and they seem to show that Antarctica has 

 taken a very important part in fern history. 



III. Musci. 



In his analysis of the Alagellanian moss flora Cardot (48) distinguished an 

 Antarctic element and he believed in a common origin of the floras of Magella- 

 nia and New Zealand (j). 44). Hkkzoc; (i2g) found that Juan Fernandez has "eine 

 last \-ollstandig austral antarktische Moosvegetation", but also possesses "ein paar 

 tropisch annuitende Artcn: ThysaiioDiiiriuni RicJiardi, Porothanniium fasciculaiuvi, 

 Pi)niatilla luaooslicta und ein kliacopiliDiiy The monotypical Chilean genus Lam- 

 l^yof'hylluDi was also mentioned as a genus of tropical ancestry. A circumpolar 

 austral-antarctic element is said to dominate in the moss flora of Patagonia and 

 l'\iegia; characteristic genera, also re[)resented in Juan Fernandez, are Dkraiioloma, 

 ( lota, Dindyocryf^hacd, I .cpyycuhi}!, rtycliouinium, Weyniouthia, DisticJiophylluni^ 

 r/in\^-(>/^/iyI/in//, liriof^us, J f]f(phn\i^ju»i, Sciaro))iiiu)i, perhaps also CatagoJiiopsis 

 and Psihpilii))!. Ii<ms( [ikr (//,') gives many examples of austral-bicentric taxa: 

 Lcpyrodo)itac(ai\ /\>Iy/r/i/i/i</i//^//!(s^ Wcymouthia, PtcrygopJiylluni, Sciaromiuin sect. 

 Aloma, Hyp(ptn-yo;iu))i sect. Stoiobasis, I lypnodcndron, and species of Disticko- 

 phylluui^ J ovinia, Macyoviityiuui and MielichJioferia. 



