1889.] • IVa/ks Under the Sea by a Coral Strand. 947 
{ManiccBna areolata) In the " lancet coral " the partitions or 
thin plates lining the folds are beset with sharp cutting teeth. 
The floor of a coral reef is a mosaic of living stones. The 
prevailing hues are browns, yellows and greens, which are re- 
lieved, as we have seen, by touches of bright colors. As the 
back ground of a forest enhances by the contrast the bright 
liveries of the birds and insects and the painted petals of flowers, 
so the sombre coral masses are illumined by purple alcyonaria, 
by scarlet actinia, by the vermilion heads of worms, and by the 
varied colors of the throng of animal and plant life. 
On the land as in the sea the greatest harmony of colours 
seems to prevail among those forms which are capable of the 
least motion, like the stationary trees and the solid coral-stocks, 
while the restless fish, the crabs and worms which crawl at will 
over the bottom or thrust their heads from their burrows, the 
sea-anemones which, however incapable of active locomotion, 
can so retract their bright bodies that only an obscure disc is 
seen, may all wear the richest and most varied hues. 
The meaning of colors in the organic world, if they have a 
meaning, is a subject of great interest, and it is commonly be- 
lieved that the color of many animals has been acquired by 
natural selection, and has a protective significance, which is prob- 
ably true. It has been discovered that certain insects are pro- 
tected by the extraordinary and forbidding brilliancy of their 
colors, and by assuming the colors of common poisonous spe- 
cies, thus sharing the latter's immunity from harm. But many 
phenomena which we constantly meet with are not to be thus 
explained. A case in point of much interest is that of the West 
Indian shore crab {Gregarinus ruricold). This beautiful crab 
burrows in the mangrove swamps at about the level of high 
water, and is common throughout the Bahamas. I happened to 
land at the eastern extremity of Hog Key one day in April, just 
after heavy rains had flooded the island and routed the shore 
crabs from their dwellings. Nearly every green spray and bough 
was ornamented with these handsome crabs, which were decor- 
ated in the brightest and most varied hues. Some of them have 
the legs crimson and the body a dark purple, with a large yellow 
