In this subclass—the actinoid corals—the polyps are of two kinds. The smaller are without tentacles and are called /siphonozoöids/. The larger have but eight radial partitions and eight tentacles. This limitation of parts places them in a higher rank than the corals of the first subclass. Another characteristic of these polyps is the presence of symmetrical branchlets on the tentacles, which give them a feather-like appearance. These corals are called halcyonoids. [pg151] Some of them may easily be fancied to have been selected for halcyons' nests, as the name suggests—the sea-fans, for example. ORDER =ALCYONACEA= GENUS ^Alcyonium^ ^A. palmatum.^ This coral community is found sometimes at low-water mark, but usually in deeper water, attached to shells and stones. It is commonly known as dead-men's-fingers, an unpleasant name given it by fishermen because of a fancied resemblance to a human hand with only the stumps of the fingers. The substance of the coral is semi-cartilaginous, with scattered spicules of lime which give it stability. When the polyps are fully extended the colony is rather attractive in appearance, but not so when contracted. It is found in abundance on the New England coast. An immense /Alcyonium/, /Paragorgia arborea/, grows on the fishing-banks off Newfoundland, and is sometimes brought up on the fishing-lines. It is tree-like in form, and measures six feet or more in length. GENUS ^Tubipora^ [Illustration: /Tubipora/, organ-pipe coral, natural size.] The organ-pipe coral. This genus, which is deep red in color and very fragile, consists of many tubes slightly separated from [pg152] one another, but connected by horizontal platforms at short intervals. The form of reproduction, by budding, in this colony is peculiar to itself. The spicules of lime secreted in the polyp unite or fuse into a tube or cylindrical skeleton. At certain stages of development the polyp sends out a horizontal expansion, which unites with the expansions of other polyps and becomes calcified, forming a shelf which binds the tubes together. From the top of the platforms other corallites are formed, and thus a colony is made, which broadens as it rises in its growth. The body of the polyp is green, the skeleton red. It belongs to the East Indian seas and is given here only as an example of a peculiar manner of growth. ORDER =GORGONACEA= SEA-FANS, SEA-WHIPS, AND SEA-FEATHERS These are compound, tree-like /Alcyonaria/, with a calcareous or horny skeleton which forms a branched axis and is covered with a layer of united polyps having spicules of lime distributed through the mass, which give some firmness to the bark-like covering. Gorgonias, in great variety, grow in abundance on the coral reefs and mud-flats of Florida, forming masses of low shrubbery, pink, yellow, brown, or purple in color.