442 Willis . — -The Distribution of Species in New Zealand . 
As there is a widespread impression that New Zealand has a much 
larger endemic flora than Ceylon, and one much richer in endemic genera, 
it will be well to make at the start a comparison of the actual facts. 
Table II. 
Wides. Endemics. Endemic genera. 
New Zealand 399 902 23 with 31 species. 
Ceylon 2,000 809 23 with 52 species. 
In writing this paper I have predicted, with the aid of my hypothesis 
of ‘ age and area ’, what phenomena should be looked for in the flora of 
New Zealand, and as all my predictions have been verified when it came to 
examining the facts, the result has given me considerable confidence in the 
truth of the hypothesis. We may commence with a somewhat striking 
example of this prediction and subsequent verification. As the argument 
is a trifle complex, I have simplified it by reducing it to the form of 
a diagram, which will also serve to illustrate the second prediction. 
My object was to predict what (under the age and area hypothesis) 
would be the local distribution of the endemic species of New Zealand, 
assuming that the wides entered (largely, at any rate) at some part of the 
islands, and not indefinitely all along the chain, for which supposition there 
was reasonable evidence in the soundings, which show that the shallowest 
water approaches New Zealand towards the centre of the chain of islands. 
For the sake of simplicity I have assumed that New Zealand is 1,000 
instead of 1,080 miles long, and that the point of entry of the wides was at 
the exact centre, i. e. at 500 miles. Imagining one species (w) to enter at 
this point, and to follow the law exactly, its distribution may be represented 
by drawing a triangle showing it gradually expanding till after a certain 
