834 
ORIGIN OF LIFE IN AMERICA 
but the two have many forms of mollusks in common, and 
should be regarded perhaps as sub-divisions of one faunistic 
marine area. According to Dr. von Ihering,* Chile received, 
in early Tertiary times, certain tropical genera of mollusks 
which never succeeded in attaining the North American 
coasts, yet are represented also in Patagonia, while others, 
such as Conus, Purpura, Oliva, Concholepas, Cassis, Cypraea 
and Rissoa are absent from the latter country. They are 
supposed to have travelled along the north coast of South 
America to Ecuador, Peru and Chile by means of a Central 
American marine channel. Certain species even of that an¬ 
cient marine migration have persisted to the present day, 
not only on the coast of Chile, but on the west coast of Africa 
and in the Mediterranean. Even in Miocene times the in¬ 
fluence of the Caribbean and European marine faunas was 
felt on the coast of Peru, according to Dr. Ortmann.f 
Certain northern species of the genera Saxidomus and 
Chlorostoma, says Dr. von Ihering (p. 524) did not reach the 
coast of Chile until the Pleistocene Period. Thus it seems 
manifest that during practically the whole of the Tertiary 
Era there was no Humboldt current sweeping northward 
along the west coast of South America, as it does at present. 
On the contrary, there is sufficient evidence to show that 
whatever current there existed flowed in the opposite 
direction. 
This investigation has resulted in two very important 
results, viz., firstly, the demonstration that the Humboldt 
current formerly did not exist, and secondly, that its absence 
must have been caused by profound differences in the condi¬ 
tions of land and water from those now prevailing. Of the 
nature of these changes I have foreshadowed already enough 
to enable anyone to reconstruct them. When the currents 
issued from the Caribbean Sea into what is now the Pacific, 
they must have been faced by land westward and northward. 
They could only have flowed southward. But the land which' 
lay south-westward between Central America and the Gala¬ 
pagos islands extended probably far southward, parallel to 
* Ihering, II. von, “Mollusques fossiles de T Argentine,” pp. 514—516. 
t Ortmann, A. E., “ Tertiary Invertebrates of Sta. Cruz,” p. 320. 
