116 THREE CRUISES OF THE “ BLAKE.” 
the Virgin Islands, are somewhat poorer, and as we come to the 
Windward Islands the West Indian types disappear and are re- 
placed by continental forms. In the Bahamas we find no con- 
tinental types, the species being most clearly allied to those of 
Cuba, with which geologically and physically they are in closer 
connection. 
While the flora of Florida undoubtedly has many of the char- 
acteristic features of that of the Southern States, it has also a 
decided West Indian tinge. Its mangroves, limes, and pal- 
mettos connect it with the vegetation found on the other side 
of the Straits of Florida, and along its southern extremity are 
found West Indian, Mexican, and Central American birds, 
which rarely find their way farther north than the Kverglades. 
Our imperfect knowledge of the geology of Central America 
tends to show that South America must have remained isolated 
from North America before the tertiary period; that during 
palxozoic times it formed a huge archipelago, and that its con- 
nection with North America was never a very close one. Hence 
the migration during tertiary times of many of the American 
forms has produced in the West Indies and the Central Amer- 
ican districts a strange mixture of ancient and recent types. 
Many of these are now extinct both in North and South America. 
This want of close connection between the Americas has prob- 
ably affected the fauna of South America much as it has that 
of the West Indies, and produced conditions highly favorable to 
the extraordinary development of specific forms, which charac- 
terizes the fauna of tropical America beyond all other faunal 
districts. 
The deep soundings (over three thousand fathoms) developed 
by the “Blake” south of Cuba, between that island and Yuca- 
tan and Jamaica, do not lend much support to the theory of an 
Antillean continent as mapped out by Wallace, nor is it prob- 
able that this continent had a much greater extension in former 
times than now, judging from the depths found on both sides of 
the West India Islands. This would all tend to prove the want 
of close connection between the West India Islands and the ad- 
joining continent. It leads us to look, for the origin of the 
fauna and flora of those islands, to causes similar to those which 
