31 
seemed ideal for successful work with the marine flora — except 
for the one unhappy fact, which gradually became apparent, that 
a marine flora, in the ordinary sense, was in that region almost 
non-existent. The vertical rise and fall of the tide on this and 
the adjacent islands appeared to be, while we were there, from 
twelve to fifteen feet, but at the ebb of the tide, the pools, and 
the rocks and stones, both above and below the low-water line, 
were seen to be nearly destitute of plant life —at least, of con- 
spicuous species. And not a fragment of an alga or of any 
marine seed-plant was found washed ashore at any point in the 
part of the Bay of Panama that was examined. There were a 
few closely incrusting species of Ralfsia, Hildenbrandtia, Squa- 
mariaceae, Corallinaceae, and Cyanophyceae, and certain minute 
filamentous and unicellular forms representing various groups of 
algae. The material secured has not been critically studied as 
yet, but it would probably not be far out of the way to say that 
no more than fifty species of marine algae were seen and collected 
during the week that was spent in exploring the shores of Taboga 
Island and of the adjacent islands, Urava and Taboguilla. The 
cause of the paucity of marine plant life in this region is not 
wholly obvious. The scorching effect of the direct rays of the 
tropical sun is of course unfavorable to any luxuriant develop- 
ment of the algae between the tide-lines, as is abundantly demon- 
strated in the West Indies, yet, a priori, one might reasonably 
expect to find here a considerable growth of plants near the low- 
water line, as in corresponding latitudes in the West Indies and 
as, indeed, only fifty miles or less to the northward on the Carib- 
bean shores, even though it be on the shores of another ocean 
and on the opposite edge of a continent. The only obvious factor 
in which the conditions are manifestly different on the opposite 
shores of the Isthmus is found in the range of the tides. In the 
Bay of Panama the tides have a maximum vertical range of from 
ten to nineteen feet ; at Colon, on the Atlantic or Caribbean side, 
the range is commonly less than two feet. On the borders of 
the Caribbean Sea there is often an abundance of algae in water 
that is much deeper than that which at flood tide covers the 
rocks at low-water line in the Bay of Panama, but it is clear that 
