654 Original Articles. [ Oct., 
breeding Mammals. It is true that butterflies might continue to find 
their way from Africa to the island across a space of sea which had 
long since proved an impassable barrier to any but aérial Mammalia, 
but the influence which might thus be at intervals brought to bear on 
the insular Rhopalocera would be very slight, for the idea of constant 
or long-continued migration from the mainland is forbidden by all 
recent observation. * 
In conclusion, I would earnestly request all zoologists to contribute 
the results of their researches towards the more complete knowledge 
of the fauna of Madagascar. Dr. Sclater’s interesting deductions from 
a consideration of the Mammalia, require abundant confirmation from 
investigation of other groups in the island fauna, before acceptance 
can be given to them. The subject is one of the deepest interest ; and 
it is only by a careful analysis of what is known of all the forms of 
Madagascarian life that we can attain to any conclusions as to the origi- 
nal derivation and existing relations of this most remarkable fauna. 
* It is remarkable how constant nearly all butterflies, including those of the 
highest powers of flight, are to localities of very limited extent; and much care 
and investigation must be exercised before naturalists can attribute the extraordi- 
nary gatherings, occasionally witnessed, of certain species of Pieride to any migra- 
tory instinct. 
