MA CROLEPIDOPTERA 



133 



It is to be observed that none of the genera of the first and second periods, except 

 Agrotis, and only about half the genera of the third period can be esteemed strong 

 on the wing ; these must therefore in general have proceeded by way of intermediate 

 islands. Moreover, nearly all the genera of decided American origin, in whatever 

 period, possess this characteristic of strong flight, and as the trade-winds must always 

 have existed, there seems no reason to suspect the previous existence of any inter- 

 mediate islands between Hawaii and N. America. 



Inter-Island Distribution of Species. 



The following statistics relate only to the 261 endemic species. No doubt further 

 exploration would extend the inter-island range of some species, but probably new 

 species of restricted range would be discovered in an equal proportion, so that the 

 general results may be taken as fairly representative. 



Of 4 species taken by Mr Blackburn the localities have not been recorded ; I 

 suppose 3 to be from Maui and i from Oahu, but they are not included hereafter ; the 

 total may then be taken as 257. 



Of these 173, or more than two-thirds (67 per cent.), are confined each to a 

 single island. The whole number of species occurring in each island, the number 

 of peculiar species, and the proportion between the two numbers, are given in the 

 following table : 



Of the remaining 84 species, 36 have been taken both in Hawaii and Kauai, at 

 opposite ends of the group, and usually in one or more of the intermediate islands ; 

 they may therefore be counted as ranging throughout the group. The distribution 

 of the others is as follows : 



Hawaii, Maui 



Hawaii, Maui, Lanai 



Hawaii, Maui, Molokai 



Hawaii, Lanai 



9 



I 



3 

 4 



