Willis. — Plant Invasions of New Zealand . 475 
Island. These species with northern entry are fairly easily segregated from 
the rest of the flora. 
As already indicated in (10), p. 356, Table I, we may look upon about 
thirty-three families of the ninety-one of the New Zealand flora as showing 
this northern maximum. But it would be a great mistake to assume that 
all members of these families entered from the north. So many of them 
show a northern maximum that their figures swamp those of any that may 
have entered in any other way, but a more satisfactory result is obtained by 
going through the figures genus by genus. Even then one finds genera in 
which there are some wides with evident northern entry, and others with 
equally evident entry by some other route, but these are few in comparison 
with the total, and for the present it is better not to attempt to go into too 
minute detail. 
Examining the whole of the ^7 1 r-j 
genera of the New Zealand flora as {ford. Howe 1$ Kermcuiec ij P j 
given by Cheeseman (all the larger V 
of them are given in Tables V and 
VI of ( 9 ) ), I have arrived at the 
general tentative result given in 
Table II below. While the northern 
types seem to divide into a northern 
(proper) and a Kermadec invasion 
(11, p’ 279), the rest seem to me to s'te-waf ip^ 
split into a western and a southern / * snares .Boymyi 
invasion, a considerable number / •BcfcZan&J. , _ 
/ ^ , , 7 j ^'LArmpocLes I 
(western) having their centre of / 
greatest density between 4-500 and * 1 
6—700 miles from Noith Cape , foi Diagram 2. New Zealand and outlying islands, 
instance, Drimys , Coprosma , and The dotted line is the 1,000 fathom limit. 
Pimelea in Table I. In such cases 
the very marked tapering off of the numbers both to north and to south makes 
it fairly probable that they must have commenced at the middle, but these 
genera run imperceptibly into those of the more southern group which we 
have already considered in a previous paper, so as to render it very difficult 
in many cases to separate them. A glance at the map, showing the broadly 
triangular way in which the water of less than 1,000 fathoms meets the west 
coast of New Zealand, will help to make it more clear why this should be so. 
But I am inclined to think, none the less, that my figures indicate that there 
were probably two different invasions, a western and a southern. At the 
time when the greater part of the sea floor to 1,000 fathoms was dry land, 
it is clear that a species arriving at the point where stands the N of ‘ North I.’ 
would be able to spread out fanwise, and might ultimately reach (the 
existing) New Zealand along a wide front. 
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