536 The American Naturalist. [June, : 
West Indian, 
Cuban, 
Haytian, 
Porto Rican, 
Central American, 
Uncertain, 
a Aime O N 
UON wm OO 
(o = E -SELD BA) 
We have said that the formation of the fauna we have just 
reviewed has, in the case of thé land-bird element, been caused by 
more or less fortuitous circumstances. This in a measure is true. 
Inaugua on the south is distant from Cuba and Hayti about fifty 
miles, Great Bahama on the north is distant from Florida sixty 
miles, while these islands are situated respectively thirty and ten 
miles from their nearest neighbors in the group. These in turn 
are separated. from others by varying distances, never greater, 
however, than the distances first mentioned. Of Great Bahama 
we know nothing; no ornithologist has ever visited it. Of 
Inaugua, we have some knowledge, and it has apparently served 
as a gateway for many species of West Indian origin which are 
now distributed throughout the Bahamas. Others, ‘four in num- — 
ber, have not advanced beyond this portal. Once established on 
Inaugua, the most difficult step would have been taken, and future 
_ ones become comparatively easy. It is not assumed that all the : 
Bahaman species of West Indian origin have been derived = 
through Inaugua, though it is evident that some of them have, e 
and we may in this way, through a northward movement among 
the more eastern islands, account for the distribution of the 
Cuban parrot, which is found on Abaco, but is unknown on 
Andros. We mention this island merely as a possible first step 
for future Bahaman birds. Our examination of the fauna renders 
in a degree apparent the chief cause which promoted this step. 
As a rule, the land birds of oceanic islands have descended — 
from | or are non-sedentary species, whose habits render them = 
ject to the influences of storms or trade- winds, the most po . 
factors in the formation of insular avifauna. For this reason 
we should not expect to find species of especially sedentary 
disposition forming a prominent part of an island fauna. © 
entary is not a here as meaning non-migratory alone, bu 
