( apiiy » 
In temperate and cold regions, the prevalence of regular 
seasons having a warm and sunny summer, with a dry and 
cold winter, and in tropical regions abundant rainfall, coupled 
with sufficient sunshine, being the conditions which favour 
abundance of individuals, A great range of elevation in a 
limited area has an overwhelming influence on the number 
and variety of genera, 
One would reasonably suppose that as the greater number 
of Lepidoptera depend on plants alone during their laryal 
stage of existence, their distribution would closely coincide 
with that of plants. So far as I am able to judge, how- 
ever, the general features of their distribution agree far 
better with that of birds than with that of plants. 
The best general reswmé of the distribution of the plants 
I know is that by Mr. W. B. Hemsley, F.R.S., in his intro- 
duction to the botanical part of ‘ Biologia Centrali-Americana,’ 
published in 1888; and I am glad to see that in this 
admirable paper the same principle of working out the facts 
is adopted that I had previously used in 1873 in my paper 
on the ‘ Distribution of Asiatic Birds,’** namely, by per- 
centage. Wallace states that nothing like a_ perfect 
Zoological division of the earth is possible, and in this I 
quite agree with him. But when Wallace, Sclater, and 
Sharpe are so nearly agreed, the main difference between 
them being that Sclater makes the Pacific region separate 
from the Australian, whilst Wallace and Sharpe unite them 
as a primary division, it is clear that there cannot be any 
great error in their conclusions. 
Hemsley suggests two alternative schemes, in one of which 
he admits as primary botanical regions the following :— 
1. Northern, corresponding to the Palearctic and Nearctic 
regions of Wallace, Sclater, and Sharpe. 
2. African, corresponding to their Ethiopian region. 
3. Indian, corresponding to their Indian region, with the 
addition of the Austro-Malay sub-region of Wallace. 
* Proc. Zool. Soc , 1873, pp. 645—682. 
