284 



C. SKOTTSBERG 



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

 were of tropical origin tiiey 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-day, this fact is a strong indication of its Antarctic origin and that, if the pre- 

 sent range is wholly 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 present distribution, because tropical and northern species must outnumber the whole 

 flora of Antarctic America, or even of New Zealand [dy. 158). 



With this he wants so say, I suppose, that a vigorous family has invaded the 

 tropics and also extended north under rapid evolution of genera and species con- 

 cealing the primary origin; he believes this evolution to have been so rapid that 

 the period 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 or 

 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 assumption that this has been the chief place of evolution obviates the neces- 

 sity of assuming and explaining migration in latitude. It is only when we open our 

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

 comes necessary (d/. 163). 



Great geographical disjunctions, of which the Juan Fernandez fern flora offers 

 many 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 Magellanian moss flora Cardot {48) distinguished an 

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

 nia and New Zealand (p. 44). Herzog [i2g) found that Juan Fernandez has "eine 

 fast voUstandig austral-antarktische Moosvegetation", but also possesses "ein paar 

 tropisch anmutende Arten: Thysa?tomiirmm Richardi^ Porothanmiiim fasciculatuvi ^ 

 Pi7inatella macrosticta und ein Rhacopilumy The monotypical Chilean genus Lam- 

 prophylliwi 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 

 Fuegia; characteristic genera, also represented in Juan Fernandez, dixe Dkraiio/onia, 

 Ulota, DendrocrypJiaea, Lepyrodon, Ptychoninium, Weyiiiouf/na, Distichophylluvi^ 

 Pterygophyllum, Eriopus, Hypopterygium, Sciaronium , perhaps also Catagoniopsis 

 and Psilopihmi. Irmscher {143) gives many examples of austral-bicentric taxa: 

 Lepyrodontaceae, Polytrichadelphus , Weymoutliia, Pterygopliylhan, Sciaromiuin sect, 

 Aloma, Hypopterygiuni sect. Stenobasis, Hypiiode7idroit, and species of DisticJio- 

 phylluiii, Tortilla^ Macromitritim and MielicJilioferia. 



