Willis. — Plant Invasions of New Zealand. 489 
(14) In the same way they should belong to the larger genera of the 
island floras. In actual fact, they belong to 81 genera which contain 
altogether 150 species, or i*8 species per genus. The genera that contain 
no endemics are 125 with 152 species, or i*2 species per genus. 
(15) One will expect the island genera which contain endemics, 
nasmuch as they will on the whole be old, to be fairly large in New 
Zealand (when they reach there). There are 81 in all of them, and 37 do 
not reach New Zealand. The remaining 44 contain in New Zealand 362 
species, or an average of 8*2 species per genus, while the average size of 
a genus in New Zealand is only 4-2 species. Even if the 362 be divided 
by the whole 81, the result is 4*4. 
It is worthy of note, with reference to Professor Sinnott’s hypothesis of 
‘swamping’ (6, p. 214), that of the 362 species in New Zealand only 38 are 
wides. But on the other hand, the genera which are represented by wides 
in the islands are usually represented by wides in New Zealand. 
(16) One will expect the families with endemics in the islands to be on 
the whole the same as the families with endemics in New Zealand, being 
the older families in each case. In New Zealand 7 6 families out of 91 
contain endemics, but of these 18 (10, p. 359) are chiefly southern. In the 
islands 49 families contain endemics, and of these 38 are the same as in New 
Zealand. The other 11 include Sterculiaceae, Celastraceae, Styracaceae, 
and Asclepiadaceae, which do not occur in New Zealand, a-nd also Cucurbi- 
taceae,Goodeniaceae.Shpotaceae,Convolvulaceae, Amarantaceae, Piperaceae, 
and Amaryllidaceae, 7 families with only 17 species in all, and 15 of them 
wides, while the average range in New Zealand is only 587 miles (against 
a possible range of 1,080), all of them facts which point to the probably 
(comparatively) recent arrival of these families in New Zealand. 
(17) In the same way, the genera with endemics in the islands should 
in general be genera that have endemics in New Zealand, or genera 
probably only comparatively recently arrived there. Of the 81 island 
genera with endemics, 37 do not occur in New Zealand, leaving 44 that do, 
of which no fewer than 38 possess endemics in New Zealand. It may be 
said, by those who have not worked at the matter in detail, that this is 
probably only the normal percentage of New Zealand genera that possess 
endemics, but in actual fact 95 genera out of 321 have no endemics in New 
Zealand, or a much higher percentage. The 6 genera that have no endemics 
in New Zealand are Hibiscus, Ipomaea , Calystegia , Solarium , Peperomia , and 
Euphorbia , which have in all 12 wides with an average range of 647 miles, 
and are thus small and slightly ranging genera, therefore probably on the 
whole young in New Zealand (in their affinity groups). 
(18) One will expect the endemics of the islands to belong chiefly to 
the families that reach most islands. 
