Willis.— Plant Invasions of New Zealand. 485 
(7) One will also expect to find that the 209 species that do not reach 
New Zealand will be largely members of genera and still more of families that 
do reach it. Those families and genera that reach New Zealand will on the 
whole be the earliest arrivals of their respective affinity groups. These 
groups will thus, so to speak, have the start of the others, and there will be 
more likely to be more of them in the islands than of other groups, of which 
none have reached New Zealand. Testing this we find in the island flora : 
Table V. 
Not reaching N.Z. 209 species of 155 genera and 74 families 
Found in N.Z. of these (none) 64 ,, (with 130 spp.) and 58 families 
Leaving 91 „ „ 112 „ „ 16 „ 
(8) One will expect to find the families and genera that have reached 
New Zealand better represented in the islands, on the whole, as being older, 
than those that have not. 
Table VI. 
The 58 families contain 137 genera, or 2*3 genera per family 
,, 16 ,, 18 ,, i*i ,, 
„ 64 genera contain 130 species, or 2*0 species per genus 
>> 9 1 >> 113 >> 1,3 }) 
(9) The 16 families that do not reach New Zealand at all, are all, as 
one would expect (they being probably young, and therefore on the average 
small, in the islands), small and not widely distributed in the islands. They 
are Menispermaceae (1 sp. Howe), Capparidaceae (1 Norf.), Bixaceae 
(1 Howe), Frankeniaceae (1 Norf.), Sterculiaceae (1 Norf.), Celastraceae 
(1 Norf., 1 Howe), Lythraceae (1 Norf.), Plumbaginaceae (1 Norf.), Styra- 
caceae (1 Howe), Asclepiadaceae ( % on Howe only 1 Norf., 1 Howe), 
Bignoniaceae (1 Norf., 1 Howe), Acanthaceae (1 Howe), Hydrocharidaceae 
(1 Howe), Commelinaceae (1 Norf., 1 Howe), Flagellariaceae (1 Howe), 
Araceae (1 Norf.). All. are small, and little distributed among the islands. 
Similarly, of the 91 genera, 65 have only one species reaching one island, 
10 one species reaching two. 
(10) Of the 91 genera that do not occur in New Zealand, one will 
expect the greater proportion (both absolute and per family) to belong to 
families that have reached New Zealand, for these will be the older families 
in their affinity circles. In actual fact 73 belong to 42 families that have 
reached New Zealand, or four-fifths of the total, and 1*7 genera per family, 
while 1 8 belong to 16 families that have not reached New Zealand, or one-fifth 
of the total, and i*i genera per family. The prophecy is thus borne out. 
(11) To turn now to another type of consideration, one will expect the 
bulk of the floras of these islands to belong to genera and families that in 
Table II are marked as probably belonging to northern, Kermadec, or 
