The royal natural history . from the rest of thebody-cavity, and often coiling round inside it. In this respect the Echinodermsresemble all the animals that have been dealt with in the preceding pages,whereas the jelly-fish and their allies differ from them in having no body-cavityseparated off from the stomach and its processes. Moreover, Echinoderms resemblethe higher animals in the possession of a system of branched tubes conveying bloodthrough the body. Examining a star-fish or a sea-urchin, one sees, on the under surface of the raysin the former, and passing in five bands from top to bott
The royal natural history . from the rest of thebody-cavity, and often coiling round inside it. In this respect the Echinodermsresemble all the animals that have been dealt with in the preceding pages,whereas the jelly-fish and their allies differ from them in having no body-cavityseparated off from the stomach and its processes. Moreover, Echinoderms resemblethe higher animals in the possession of a system of branched tubes conveying bloodthrough the body. Examining a star-fish or a sea-urchin, one sees, on the under surface of the raysin the former, and passing in five bands from top to bottom of the latter, a numberof small cylindrical processes, which are usually gently waving about like trees ina wind. They lie in each band, or in each ray, along two rows, with a clear spacebetween, like trees on either side of an avenue; hence the whole band of them ineach ray is called an ambulacrum (garden-walk). Most of these little processesend in sucker-like discs, which the animal can stretch out and attach to smooth. anchor sea-cucumber {Synapta), a, Tentacles round the mouth ; e, Anchor- and plate-shaped spicules; b, c, d, Similar spicules of anallied form. OS! GENERAL CHARACTERS, 291 surrounding objects; and it is thereby able either to hold itself firm against wavesor currents, or to pull itself along. Hence these processes are usually called
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Keywords: ., bookcentury1800, booksubjectnaturalhistory, booksubjectzoology
