. Birds of other lands, reptiles, fishes, jointed animals and lower forms;. Zoology; Birds; Reptiles; Fishes. 352 THE LIVING ANIMALS OF THE WORLD pre\'iously referred to. In some, \\hile the sub-spheroidal form of the case, or test, is still retained, the external spiny armature is greath' varied. In one series these spines are exceedingl)' long, slender, and of needle-like contour and sharpness. In others, while long, they are abnormally thick and c_\'lindrical, somewhat resembling slate-pencils, for which they are sometimes used as a substitute; or they may be club-shaped, branched, or reduc
. Birds of other lands, reptiles, fishes, jointed animals and lower forms;. Zoology; Birds; Reptiles; Fishes. 352 THE LIVING ANIMALS OF THE WORLD pre\'iously referred to. In some, \\hile the sub-spheroidal form of the case, or test, is still retained, the external spiny armature is greath' varied. In one series these spines are exceedingl)' long, slender, and of needle-like contour and sharpness. In others, while long, they are abnormally thick and c_\'lindrical, somewhat resembling slate-pencils, for which they are sometimes used as a substitute; or they may be club-shaped, branched, or reduced to flattened plates. In other forms the shell itself is conspicuousl}' modified. With some known as Biscuit- or C-\KE-URCHIN,s it is flattened out to the resemblance of a cake or biscuit, the spines being minute and inconspicuous. In another group, distinguished as , the shell is oval and bilaterally symmetrical, though the dominant number of five still holds good with regard to the building up of its structural details. One of the most interesting is the Le.\THER-URCHIN, so called on account of the flexible and loosely jointed character of its shell, the wa)- being paved by such a form to the normally soft- and flexible-skinned sea-cucumbers. Sea-urchins are to a great vegetable-feeders, and the larger species are appreciated as an article of food in man\' countries, the ovaries, or roe, with which at certain periods the shell is mostly filled^ forming the edible portion. The Sea-cucumbers — better known in the commercial world as Beche-de-mer, orTrepang — represent the onh' group which possesses a substantial market-\'alue. Its typical members present an elongate A\'orm-like contour, but pro- gress b}- means of extensile tube-feet, after the manner of the Urchins and Star-fishes, and ha\'e their dental, ncr\'ous, and muscular systems fashioned on the same fi\'e-sectioned basis. The mouth, which is situated at one extremity of the body, is surround
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Keywords: ., bookcentury1900, bookdecad, booksubjectfishes, booksubjectzoology
