436 THE POPULAR SCIENCE MONTHLY 
than 200 fathoms, and that the bottom forms of the deep-sea do not 
rise more than 60 fathoms above the floor of the ocean, and that there 
is practically no life between 200 fathoms below the surface and 60 
fathoms above the bottom. His later studies have, however, shown that 
these conclusions must be modified, for in the tropical Pacific surface 
forms are sometimes taken at a depth of about 300 fathoms beneath 
the surface, and although the surface animals do not commonly sink 
to depths greater than this, there is apparently a most interesting in- 
termediate fauna of meduse, etc., which are sometimes found at depths 
greater than 400 fathoms and which rarely or never rise to the surface. 
Agassiz clearly saw the complexities and difficulties of this problem, 
and realized that its solution can be reached only after many have 
labored upon it. Indeed, he himself was forced through lack of time 
to abandon its study to others. , 
A yery rich collection of deep-sea forms then new to science was 
made by this expedition of the Albatross and have been described in 
numerous papers in the “ Bulletins” and “ Memoirs” of the museum 
at Harvard. 
The most important general result was Alexander Agassiz’s dis- 
covery that the deep-sea animals of the Gulf of Panama were more 
closely allied to those of the depths of the Caribbean Sea than the Carib- 
bean forms were to those of the deep waters of the Atlantic. This leads 
him to conclude that the Gulf of Panama was once more intimately 
connected with the Caribbean than the latter is with the Atlantic, and 
thus the Caribbean Sea was at one time merely a bay of the Pacific, 
and has become shut off since Cretaceous times by the uplifting of the 
Isthmus of Panama. 
In 1892 Alexander Agassiz published his general report upon this 
important exploration of the Panamic region, and he concludes that 
the Galapagos Islands have never been connected with the mainland 
of America, but that the ancestors of their peculiar animals and plants 
were drifted over the ocean by the prevailing winds and stranded upon 
the shores of these remote islands. He also observed that the animals 
of the deep sea are preponderatingly reddish or violet in color, and 
that blue-colored forms, such as are observed on the surface, are rare 
in the depths. This inclines him to suspect that the lingering rem- 
nant of sunlight which penetrates into the depths is red, but in view 
of the absence of observation he is cautious in advancing this sugges- 
tion. 
Another paper of 1892 is his description of an interesting crinoid 
from the depths of the sea near the Galapagos Islands. This is a 
highly generalized form, and it is beautifully painted from life by 
Westergren, who accompanied him as artist upon the Albatross. In 
1898 and 1904 he describes the deep-sea echini found off Panama, this 
