526 ISLAND LIFE 



PART II 



in the distribution of all forms of life. Just as we explain 

 the presence of marsupials in Australia and America and 

 of Centetidae in Madagascar and the Antilles, by the pre- 

 servation in these localities of remnants of once wide-spread 

 types, so we should prefer to consider the few genera com- 

 mon to Australia and South Africa as remnants of an 

 ancient vegetation, once spread over the northern hemi- 

 sphere, driven southward by the pressure of more special- 

 ised types, and now finding a refuge in these two widely 

 separated southern lands. It is suggestive of such an ex- 

 planation that these genera are either of very ancient 

 groups — as Conifers and Cycads — or plants of low organ- 

 isation as the Restiaceae — or of world-wide distribution, as 

 Melanthaceae. 



The Endemic Genera of Plants in New Zealand, — Returning 

 now to the New Zealand flora, with which we are more 

 especially concerned, there only remains to be considered 

 the peculiar or endemic genera which characterise it. 

 These are thirty-two in number, and are mostly very 

 isolated. A few have affinities with Arctic groups, others 

 with Himalayan, or Australian genera ; several are tropical 

 forms, but the majority appear to be altogether peculiar 

 types of world-wide groups — as Leguminosse, Saxifrageae, 

 Compositae, Orchideae, &c. We must evidently trace back 

 these peculiar forms to the earliest immigrants, either from 

 the north or from the south ; and the great antiquity we are 

 obliged to give to New Zealand — an antiquity supported 

 by every feature in its fauna and flora, no less than by its 

 geological structure, and its extinct forms of life^ — aflbrds 

 ample time for the changes in the general distribution of 

 plants, and for those due to isolation and modification under 



^ Dr. Hector notes the occurrence of the genus Dammar a in Triassic 

 deposits, while in the Jurassic period New Zealand possessed the genera 

 Paloiozamia, Oleandrmm, Aldhopteris, Camptopteris, Cycadites, Echino- 

 strobics, &c., all Indian forms of the same age. Neocomian beds contain 

 a true dicotyledonous leaf with Dammar a and Araiccaria. The Cretaceous 

 deposits have produced a rich flora of dicotyledonous plants, many of 

 which are of the same genera as the existing flora ; while the Miocene and 

 other Tertiary deposits produce plants almost identical with those now 

 inhabiting the country, together with many North Temperate genera which 

 have since become extinct. (See p. 499, footnote, and Trans. New Zealand 

 Inst, YoL XL 1879, p. 536.) 



