942 The American Naturalist. [November, 
storm-clouds rising fast, and blackening all the sky, are thus 
doubly felt by their effects on the sea, which transmits the deep- 
est shades that are possible in the ultramarine. Their high 
colour effects are due not only to the clarity of the sea, but also 
to those white calcareous particles, the coral sands, which the 
ceaseless grinding of the breakers on the reef is ever producing 
and ever sifting far and near over the wide sea floor. The sands 
which fill every lagoon and bay, are tossed up in long dazzling 
lines of smooth beach, and in course of time may become hard- 
ened into coral limestone like that out of which these islands are 
formed. The depth of coral waters is singularly deceptive, owing 
to the light reflected from the bottom, and there results that won- 
derful distinctness with which a varied host of living forms like 
the coral, the starfish and the sponge, can be clearly seen even at 
great depths. The remorseless green of the sturdy tropical bush 
which covers all the shores, and which knows no change of sea- 
sons, is thus relieved by a wide sea-girdle of ever varying tints. 
The Bahama Islands are all coralline ; that is they are due (pri- 
marily) to the life and growth of coral polyps, insignificant ani- 
mals when contemplated singly, but able to girdle the globe, only 
give them time and the right conditions. 
New Providence, where I spent several months in the study of 
marine life, is the geographical as well as the commercial and 
political centre of the group. It is a small, compact island, i/ 
miles long east by west, and 7 in greatest breadth. Its southerly 
half is cut by the 25th parallel of latitude, and the longitude of 
its capital, Nassau, is J'j'' 22' W., which is a little west of Wash- 
ington. While it is just without the tropic line, it is nevertheless 
considerably within the northern borders of tropical life. 
The Bahama Islands, though widely separated, are yet remark- 
ably alike in their animal and plant life, and this simularity, 
which is doubtless shared by all coral rocks and isles in West 
Indian seas, is due to like physical conditions. All of them are 
essentially rocks formed by the hardening of coral sands, usually 
low and flat, but sometimes rising into undulating hills, or mak- 
ing precipitous bluffs and shelving cliffs. 
