THE A 8 TREE A. 
573 
It is mostly a deep-water species, not unfrequent on northern European coasts, and is 
seldom procured except by means of the dredge or grapnel. Sometimes, however, it is found 
near the coast, and at the equinoctial springtides may sometimes be procured from the rocks 
which are laid bare by the receding waters. Fortunately for the collectors, it is very gregarious 
in its habits ; and when one specimen is found, others may generally be secured within a very 
short distance. It is a pretty inhabitant of the aquarium, and, as a general rule, may be 
induced to expand its long tendrils to their fullest extent, by placing a morsel of food upon 
the orifice. When properly managed it is tolerably hardy, but it does not brook inattention — 
shrinking up daily, and at last perishing hopelessly. When new to the mysteries of aquarium- 
management, I never could keep a Cup Coral more than a month. 
Ix the family Oculinidse, the corallum is branched and tree-like, and is here represented 
by the only known form, the Tuft Coral. It is very rare. 
A remarkably fine specimen is figured by Mr. Gfosse, who 
remarks that it was taken off Skye in the year 1852, entangled 
in the deep-sea-line of a fisherman. Another specimen, weigh- 
ing six pounds, has been taken in a similar manner between 
the islands of Rum and Eig. As may be seen from the illus- 
tration, the corallum resembles a massive, thickly-branched 
tree. The individual corals are about half an inch in height 
and the same in diameter. 
On the full-page illustration is seen a coral that has 
attained a singularly tree-like form, and, in consequence of 
this structure, has obtained the appropriate name of Dendro- 
pliyllia, or Tree-Coral. 
The regular branched form of this coral can be seen by 
reference to the illustration, together with the manner in 
which the individuals are set on their common stem. The 
cells are rather deep, and the animals possess tentacles 
which are cleft longitudinally. It is a native of the hotter 
seas. 
On the accompanying illustration we have some exam- 
ples of those beings which we call Madrepores. 
In the genus Madrepoka the animals are rather short, 
with twelve simple tentacles. The cells are deep, irregu- 
larly arranged upon the surface, and are crowded together 
towards the tips of the corallum, though they are scattered 
rather widely at its base. The cells are nearly .cylindrical 
in their general shape and project outwards from a centre, 
something like the grains on an ear of wheat. 
The genus Echinopora is distinguished by the peculiar 
arrangement of the cells, which are set only upon the upper 
surface of the coral. They are boldy radiated and rather 
irregular. All the true Madreporse inhabit the hot seas, and 
are most plentiful under the tropics. 
Also of great interest is the genus Astr^ea, so called 
because the animals are sown over its surface like stars in M a drepora . —Hadrepora, verrucosa, a. Little 
the heavens. The cells are decidedly short, and the tentacles 
few in number. The genus is a very large one, including many recent and fossil specimens, 
many of which aie familiar to us in the polished stones of which mantlepieces and other 
domestic ornaments are made. Owing to the vast number of the animals, and the rapidity 
with wliich they increase, the groups of Astrsea often assume enormous dimensions ; and in 
the secondary and tertiary rocks they frequently occur in such huge masses that whole rocks 
are composed of their remains. 
