952 The American Naturalist. [November, 
for ornaments, now pinned to a coral tree or wall-side or half 
concealed in the grass. 
The actinian is in fact a greatly enlarged coral polyp, but with- 
out a skeleton, and in consequence of this they can retreat so 
completely within themselves as to become almost invisible. 
Place one of these contracted discs in an aquarium of sea water, 
and a beautiful " flower " will soon unfold, to your astonishment, 
filling the whole jar. When this animal multiplies by budding 
or by division a new individual is formed like the first, and the 
two separate, so that the colonial stage is never realized. A 
common and large species {Cereactis) has a vermilion body, and 
drab, carmine-tipped tentacles. I once saw a patch of white sand 
bordered like a parterre by a row of these bright flowers on either 
side. 
To one who has not given the subject a thought, it may take 
some stretch of imagination to associate the corals with the 
popular idea of animal life, but as we see the living mass, and 
the individual polyps, opening their mouths and extending their 
fringes of waving tentacles, any doubt in the matter will probably 
be removed. The coral stock or the sea fan is in fact a colony 
of animals, as truly as a hive of bees or an ants' nest is, but the 
former is composed of individuals united by a peculiar method of 
growth, while in the latter case the indiviruals are separate and 
specialized for different labors. 
The coral polyp, which, in spite of the protests of naturalists, 
is commonly called an insect, by the popular error of including 
under this term most small and insignificant beings, is in fact fur- 
ther from the insect than the insect is from man. It starts life as 
a free swimming oval body, which hatches from an &<g'g smaller 
than a pin's head. This active embryo acquires a mouth at one 
end, and is now significantly called ^gastrula or stomach animal. 
It soon attaches itself by the opposite end to some rocky sup- 
port, and thenceforward is a prisoner. This young polyp now 
develops tentacles or feelers about its mouth, and begins the de- 
posit of lime which is to make its skeleton. This takes the form 
of a cup in which the animal rests, it being always external to its 
own skeleton. Thin partitions or septa grow inward from the 
