68 AGE AND AREA [pt. i 



only found in a short range on the north-west coast of New 

 Zealand. It is fairly clear, from the marked way in which it 

 forms an exception to the rule as regards distribution of these 

 island species, that this legend is probably the truth, and that 

 this species therefore may be regarded as an introduction, and 

 omitted from the indigenous flora. Even including it, however, 

 the average figure for the Chatham plants is 1-7. The species 

 that reach the Kermadecs show an average rarity in New Zea- 

 land represented by 3-6, and as each 0-1 represents 12 miles in 

 range, this means that they range New Zealand on the average 

 228 miles less than the Chatham species. Their range, however, 

 is still much greater than the average for the species of New 

 Zealand as a whole, which is represented by 5-6, or 240 miles 

 less than the Kcrmadec species. The number of species in the 

 different classes ranges down to class 7, and in class 9 there is 

 again a species which may be looked upon as an exception 

 — Ij)07noea palmata, which is possibly carried by sea currents, 

 and may have reached both Kermadecs and New Zealand in 

 this way, as they are washed, where it occurs, by the same 

 current. 



Lastly, the species that reach the Aucklands (only) show an 

 average rarity in New Zealand represented by 3-5, or practically 

 the same as the range of the Kermadec species, with the lowest 

 species in class 4. The prediction as to range in New Zealand of 

 the various species reaching the islands is thus fully verified, and 

 this success lends great support to the hypothesis of Age and 

 Area. There is no conceivable reason Avhy ranging to one or 

 more of these little groups of islands, and to any one of them^, 

 though they differ Avidely in climate and geology, should make 

 a species more widespread in New Zealand than the average, 

 unless it be the mere fact that to have been able to reach the 

 islands at all it must have been above the average age in New 

 Zealand, and thus have had more time in which to spread. 



This is confirmed by the fact that there are in New Zealand 

 many species, both widely distributed (reaching Australia, etc.) 

 and endemic, which do not reach the islands at all. These by 

 hypothesis should be younger, each of course, as already ex- 

 plained, in its own circle of affinity, than the species which reach 

 the islands, and should therefore be less widespread in New 

 Zealand. There are 213 such "wides," and they show an average 



^ Kermadecs in latitude 29°-15, volcanic; Chathams in 44°-20, schists, 

 volcanic and tertiary ; Aucklands in 50°-35, igneous, mostly volcanic. 



