. Comparative zoology, structural and systematic : for use in schools and colleges. Zoology; Anatomy, Comparative; Physiology, Comparative. 256 COMPARATIVE ZOOLOGY. tween reef and shore; encircling, where there is a small island inside of a large reef; and coral islands, or atolls, where there is simply a reef with no knd inside of it. All reefs begin as fringing-reefs, and are gradually changed into the other forms by the slow sinking of the bottom of the ocean. This sinking must be slower than the upward growth of the reef, else it will be drowned out. Probably the reef does not grow more th
. Comparative zoology, structural and systematic : for use in schools and colleges. Zoology; Anatomy, Comparative; Physiology, Comparative. 256 COMPARATIVE ZOOLOGY. tween reef and shore; encircling, where there is a small island inside of a large reef; and coral islands, or atolls, where there is simply a reef with no knd inside of it. All reefs begin as fringing-reefs, and are gradually changed into the other forms by the slow sinking of the bottom of the ocean. This sinking must be slower than the upward growth of the reef, else it will be drowned out. Probably the reef does not grow more than five feet in a thousand years; and, as reefs are often more than two thousand feet thick, they must be very old. (2) Sclerobasic Corals.— Cor allium ritbrum, the precious coral of commerce, is shrub-like, about a foot high, solid throughout, taking a high polish, finely grooved on the surface, and of a crimson or rose-red color. In the living. Fig. 208.—Sea-fan (Gorgonia) and Sea-pen {^ennututa). state the branches are covered wTith a red coenosarc stud- ded with Polyps. Gorgonia, or " Sea-fan," differs from all the other representative forms in having a horny axis covered with calcareous spicules. The branches arise in the same vertical plane, and unite into a beautiful net- Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Orton, James, 1830-1877; Birge, E. A. (Edward Asahel), 1851-1950. New York : Harper & Bros.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1883
