the Outlying Islands of New Zealand . 331 
chief factor. Further, in the last column, it will be noticed that though the 
numbers increase upwards, the highest is not in class 1, which reach 
Stewart Island, but in class 2, which range only the two main islands. 
This goes to indicate comparative youth, Stewart having been cut off before 
many of the plants could reach it. 
It is thus clearly evident that the distribution in New Zealand of the 
Australian wides goes, not with the area covered in the world in general, but 
with that covered in the New Zealand archipelago, which was entered 
probably by a comparatively narrow connexion with Australia. This, it 
seems to me, completely excludes any explanation based on Natural 
Selection, whilst youth and area can only be made to explain it with the aid 
of supplementary hypotheses. It excludes the idea of absolute youth, and 
youth within the country is too far-fetched an idea to be tenable. 
We may now go on to the species endemic to New Zealand and 
the islands, which in the previous paper were treated as wides. They 
occur nowhere else in the world. They, on my hypothesis, are younger 
than the wides already dealt with, and should be fewer in proportion to the 
endemics of New Zealand proper than was the case with those wides. In 
actual fact they are 98 to 902, against 78 to 213. None of them reach all 
three of the chief island groups, and only 19 reach two (8 the Kermadecs 
and Chathams, 11 the Chathams and Aucklands). It is therefore safer to 
reason from them as a whole, and they give the following table : 
Table II. 
Class . 
Range in N . Z . 
Species . 
1 
1001-1080 m. 
4 i 
2 
881-1000 
21 
3 
761-880 
8 
4 
641-760 
7 
5 
521-640 
5 
6 
401-520 
6 
7 
281-400 
2 
8 
161-280 
3 
9 
41-160 
10 
1-40 
5 
This gives an average rarity of 2-9 ; that is to say that, though confined 
to New Zealand and the islands only, they are far more common in 
New Zealand than the average of all the wides (3*5). The difference 
of o*6 represents a range of 72 miles per species more than the mean 
range of the wides (760 m.). But in actual fact they should rather be com- 
pared with the 301 wides that are left after their removal, and these have an 
average range of 24 miles less, or 7 36 m. The dispersal of these endemics, 
however, as is required by my hypothesis, is less widespread than that of 
the wides which also go to the islands, which, if all be added together, gives 
a rarity of 1*9, or 120 miles more than the endemics (2-9). 
