Species and other Controversial Points . 201 
elusive, is given in a forthcoming paper on the islands surrounding New 
Zealand. 
1 . Dispersal of Plants in New Zealand. All the evidence goes to 
show that at one time the islands of New Zealand were continuous, but that 
at some time — whether before or after the separation from Australia is 
immaterial — they became separated by the formation in the centre of what 
is now termed Cook’s Strait. If the endemics be the older, therefore, 
it necessarily follows that Cook’s Strait would less often interfere with their 
dispersal through New Zealand than with the dispersal of the (younger) 
widely distributed species. Taking the distribution of the wides and ende- 
mics of New Zealand, zone by zone, in the same way as was done in my 
New Zealand paper (7), we find 
Wides 209 210 237 237 235 242 236 227 215 204 1 12 
Endem. 334 280 330 368 386 537 533 537 516 414 130 
to N.Z. 
From the first line it is impossible to tell where Cook’s Strait lies, whether 
after the 5th, 6th, or 7th number, but a glance at the second line shows 
a great change after the 5th, and this is in actual fact the position of Cook r s 
Strait. Many endemics come up from the south and stick at the strait. 
Similarly at Foveaux Strait, which comes between the last two figures, 
more than half the wides get across, and a much smaller proportion of the 
endemics. It is difficult to resist the conclusion that the wides, not the 
endemics, are the older. 
Another very difficult problem for the supporter of Natural Selection is 
to explain why in this table the maximum of the wides coincides in position 
with that of the endemics. One would not expect to find this, if the former 
are driving in the latter. The same is the case in Ceylon ; for more ende- 
mics occur in the wet zone, which also has by far the most wides. Even 
within the wet zone, the maximum number of both endemics and wides 
occurs in the same region. 
Why, again, do both wides and endemics taper off with very fair 
regularity towards the ends of New Zealand, and why do the numbers taper 
down much more rapidly in the case of the endemics ? While the wides sink 
from 235 to 209, the endemics sink from 386 to 234. Age and area will 
explain all this quite simply, but neither youth and area nor Natural Selection 
will do so. 
2. Distribution of the Tristichaceae and Podostemaceae. These families 
afford an excellent test case for the question of age or youth, for owing to 
their peculiar morphology one can say with reasonable approach to certainty 
which are the older forms. He would be a bold man who would say that 
such forms as Lawia in the one family, or Castelnavia in the other, with 
their violently dorsiventral structure, shown in the lichen-like vegetative 
