DHE ROLVEEETS. 95 
white, and then green. The tentacule, which are somewhat tri- 
angular, are nearly transparent, and resemble festoons of fine lace, 
fringed with a light border, and each terminated by a white pea. 
CARYOPHYLLIA SMITHII. 
The Madrepores proper are a most wonderful association of polypes, 
most varied and most interesting. If we conceive a honeycomb 
turned into stone, and a polype in each cell, we shall have a fair 
idea of the most common of the madrepores—the Astrea. The 
THE ASTRAA,. 
(Astrea pallida.) 
Meandrinz differ from the Astraa in having the surface hollowed 
out into shallow, sinuous, elongated channels. The cells are 
arranged regularly in these valley-channels. 
The Porites have their stems a little raised; they are generally 
dichotomous with obtuse lobes. The polypes are miniature 
anemones, having round their mouth twelve radiate tentacles. 
