278 
ORIGIN OF LIFE IN AMERICA 
problem. This problem has been approached from many 
other points of view. On the evidence of the fossil marine 
mollusks of the West Indian and the Mediterranean regions, 
Mr. Guppy* * * § concluded that a migration must have taken place 
right across the Atlantic along an ancient shore-line. More 
recently, Professor Gregoryf dwelt upon the intimate affini¬ 
ties that exist between the fossil sea-urchins of the West 
Indian and Mediterranean areas, and urged that it could only 
be explained by the assumption of a belt of shallow water 
across the Central Atlantic in, at latest, Miocene times. A 
few years later he adduced evidence from the fossil corals of 
Barbados, that the West Indian fauna is only a fragment 
of that of the Mediterranean Miocene, having received 
nothing from the Pacific. That this fauna did not follow 
along the shores of the North Atlantic basin is shown 
by its absence from the northern Miocene of Europe and 
America.$ Mr. Guppy§ has lately renewed the discussion of 
this subject and once more affirmed his adherence to the 
theory he expressed long ago, which has meanwhile received 
so much additional support. Even the recent marine fauna of 
the Antilles is intimately related to that of the Mediterranean. 
Some of the faunistic marine affinities between the two re¬ 
gions referred to might just as well have been produced by a 
dispersal along a land bridge between Africa and South 
America. Such, for instance, is the occurrence in early Ter¬ 
tiary deposits of the aquatic snake Pterosphenus in Egypt 
and Alabama. Dr. Andrews,|| indeed, thought it yielded an 
argument in favour of the more southern land connection. 
Let us now examine what light the recent marine mammals 
inhabiting the Caribbean Sea and the Gulf of Mexico throw on 
the problem. On the south-east coast of Florida we meet with 
one of the most curious of American mammals. With 
its seal-like head and flattened tail it is at once recognised as 
something quite distinct from other marine creatures. The 
* Guppy, R. J. L., “ West Indian Geology,” p. 501. 
t Gregory, J. W., “ American and European Echinoid faunas,” 
pp. 101—108. 
t Gregory, J. W., “ Geology of the West Indies,” p. 307. 
§ Guppy, R. J. L., “Geological Connexions of the Caribbean Region.” 
I| Andrews, C. W., “ Tertiary Vertebrates of the Fayum,” p. xxv. 
