V. 
RELATIONS OF THE AMERICAN AND WEST INDIAN FAUNA AND 
FLORA. 
A GREAT number of animals and plants date back to a time 
anterior to the present configuration of land and sea. In cer- 
tain regions we are therefore justified in looking for traces of 
ancient terrestrial or oceanic connections to explain the presence 
of identical types at isolated points." 
The explorations of the * Blake," though primarily turned 
toward the investigation of the ocean floor, had an incidental 
bearing also upon these and similar problems. The work of 
the * Blake" has added much to our knowledge of the former 
connection between South America and the West India Islands, 
and has taught us something also of the agencies which have 
helped to determine their peculiar fauna and flora. Indeed, 
hydrographic researches have given us the only acceptable 
theory of the mode in which many oceanic islands have received 
their present fauna and flora. 
According to Cleve,’ the oldest fossiliferous rocks of the West 
Indies belong to the cretaceous, and were probably deposited in 
a time of powerful voleanie action. Upon the highly disturbed 
and metamorphosed cretaceous rocks are found almost hori- 
zontal and undisturbed miocene beds. The eocene beds are 
also to a certain extent metamorphosed, while the miocene 
period must have been a period of long volcanic calm. The 
position of the most recent pliocene and postpliocene beds seems 
to indicate that some of the volcanoes now active in the West 
Indies date back to the pliocene period, others to the postpli- 
ocene. 
1 See Wallace’s “ Geographical Distri- 2 Kongl. Svensk. Vetensk. Akad. 
bution of Animals," and his “Island Handl. Bdt. 9, No. 12. 1871. 
Life.” 
