THE INTRODUCTION OF NEW SPECIES. 9 
was given by the admirable paper cf the lamented 
Mr. Strickland, published in the “Annals of Na- 
tural History,” in which he so clearly showed the 
true synthetical method of discovering the Natural 
System. 
Geographical Distribution of Organisms. 
If we now consider the geographical distribu- 
tion of animals and plants upon the earth, we 
shall find all the facts beautifully in accordance 
with, and readily explained by, the present hypo- 
thesis. A country having species, genera, and 
whole families peculiar to it, will be the neces- 
sary result of its having been isolated for a long 
period, sufficient for many series of species to 
have been created on the type of pre-existing 
ones, which, as well as many of the earlier- 
formed species, have become extinct, and thus 
made the groups appear isolated. If in any case 
the antitype had an extensive range, two or more 
groups of species might have been formed, each 
varying from it in a different manner, and thus 
producing several representative or analogous groups. 
The Sylviade of Europe and the Sylvicolide of 
North America, the Heliconide of South America 
and the Euploeas of the Hast, the group of Tro- 
gons inhabiting Asia, and that peculiar to South 
America, are examples that may be accounted for 
in this manner. 
Such phenomena as are exhibited by the Gala- 
