THE ASTR^EA. 



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. 



IN the family Oculinidfe, 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. Gosse, 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- 

 phyllia, 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 MADREPORA 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 MADREPORA .- 



tree in natural size. 



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 are 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 which 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. 



B. Cells in enlarged form. 



