Part IV. 
The History of the Flora from the Jurassic Period to the Present Time. 
1. General. 
The origin and subsequent history of the New Zealand flora is, in great 
measure, a matter of speculation merely, for the material on which Sonchisioie 
are to be based is, in no small degree, unsatisfactory and insufficient. In 
the first place, the all-important statistics as to floristic elements are, of ne- 
 cessity, drawn from existing floras, although the composition of these must 
.: »De-very different from those of the same areas in Tertiary times. It is also 
‘ assumed, in phytogeographical writings generally, that the absence of a species 
M ‚from any area means that the species in question was never there, a suppo- 
| ‚sition. quite at variance with both present happenings and fossil records. 
Again, although a certain genus has its richest development in some particular 
‚area, it does not follow that such would be the original centre of its distri- 
'bution. No phytogeographer, for example, would admit New Zealand as the 
birth-place of Veronica, its 100 or more species notwithstanding, and their in- 
_ numerable varieties. On the other hand, none would deny Celmisia a New 
Zealand origin, but is bears the appearance of a genus in process- of rapid 
\ change with many recently-evolved species, as yet hardly differentiated; indeed 
Veronica and ae are in much the same (condition from the evolutionafy 
x . Be Ä 
ee. The matter of ancient jan Eomnechone: where there are now profound. 
ocean-de 2 ing question in New Zealand biogeography. But, 
dee again, She: a is most insecure, and one can only say that the 
. ion of great changes in the relations of land and water is one on which _ 
| there, is about Be: evidence for and against. Geology can make no definite 
pro: d the matter, at present, rests solely on the facts of organic 
distribution. and whether certain eritical. examples can be clearly  explained 
ally from the zoological standpoint; HEDLEY for: nstanc 
ra to ignore the testimony of‘ ocean-depths. and 
anı es ‚on iaeeh onsiderations An Others, 
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