DERIVATION OF THK FLORA AND FAUNA 273 



We must be prepared to modify our views extensively in those cases which appear 

 to afiford fairly certain evidence of distribution from a Southern centre, but from the 

 evidence available it seems probable that such genera as Calceolaria, yovellana, Fuchsia, 

 Ourisia, Pelargonium , Caltha, Lilaeopsis, Guunera, Jlebe, Pernettya, Azorella, Drapeies 

 and other Thymelaeaceae, Nothofagus, Eucryphia, Laurelia, probably the Proteaceae, 

 some of the Ericaceae . . . may have originated in some continental area in the South 

 Hemis])here, whence their descendants spread northwards . . . 



It is of course possible that in early times many of the plants from which these 

 Southern Cienera evolved belonged to the Northern region and gradually migrated to 

 the south and having reached the Southern r'egions they there, in a state of some isola- 

 tion, evolved peculiar types which in their turn spread again northwards . . . without 

 however crossing the Equator and reaching the North Hemisphere. On this view we 

 may perhaps best regard many of the present day genera which are now only found 

 in the South Hemisphere (p. 1480). 



He adds, 



It may be almost impossible in these latter days to make any certain pronounce- 

 ment as to which natural families or genera, if any, actually originated in the Southern 

 Hemisphere, when it is remembered that there have been a succession of alternations 

 of warm temperate and cold glacial periods at various geological epochs not only in 

 the Arctic but also in the Antarctic regions. 



He thinks that the cold spells gave rise to an extensive migration south and 

 north, respectively, but he did not recognize the glaciations as contemporary in 

 the two hemispheres. 



Of other modern authors, W.H. C.\MP (7?) interests us here. My Antarcto-tertiary 

 element lists Drii)iys as a classical example of an Antarctic genus; in fact, the 

 entire family Winteraceae is supposed to be of Antarctic origin. On Camp's map, 

 however, the original seat of the family is placed in the region of the old Bering 

 Land bridge, from where tracks lead south through Asia to Australia-Tasmania 

 and through western X. America to S. America. The related Magnoliaceae are 

 circumboreal and have left numerous fossil remains in the north. Another map 

 shows Laurelia, EucrypJiia, Luzuriaga and Jovellana, all as a rule considered to 

 be Antarctic; here Cam? has two alternatives, one track leading from the north 

 as in Driviys, another from the south. Other southern families shown on his maps 

 are Tetrachondraceae, Eucryphiaceae, Centrolepidaceae, Epacridaceae (Hawaii in- 

 advertently left out), Stylidiaceae, Restionaceae, Liliaceae-Milliganieae, Philesiaceae, 

 Halorrhagidaceae and Gunneraceae. He emphasizes the fact that of the natural 

 families, some 300 in number, 103 have a fairly restricted range, and that 80 of 

 these are on the South Hemisphere. I shall quote him in full. 



In the majority of instances an analysis of a group indicates that the primitive 

 members are on the southern part of the group's range. If we were to follow the well- 

 known dicta of Matthews we could conclude that these primitive forms were "driven" 

 unto the southern land mass extremities by the more highly specialized, better adapted, 

 and more recently derived groups of the north. The natural corollary to this, therefore, 

 is that we should find the majority of the peculiar specialized and more recently derived 

 families farthest away from the primitive forms. However, as can quite easily be seen 

 in the angiosperms, in most instances this is not the case. I therefore incline to the 

 conclusion that these southern land masses are not only the original homes of the great 



18 — 557857 The Nat. Hist, of Juan Fernandez and Easter Isl. Vol. I 



