116 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 
3. The study of the distribution of species belonging to a single 
genus reveals that the more primitive or generalized species occupy a 
central position and the most specialized species are at the outer 
boundaries of the distributional area. 
4. The faunas and floras of continental islands are just what we 
should expect on the basis that there was at one time a land connection 
with the nearest continent; that at this time the faunas and floras were 
the same on both island and continent; that, later, the continent and 
island were separated by an impassable barrier of ocean; and that the 
inhabitants of the two bodies evolved separately. 
5. The faunas and floras of oceanic islands are like those of the 
nearest mainland and are of those types, for the most part, that might 
most readily have been blown or carried on floating débris. 
6. The conclusions arrived at by students of geographic distribu- 
tion, past and present, as to the existence of former land connections, 
now broken, are borne out by the independent findings of geologists 
and geographers.—Eb.] 
