Elements of zoology, or, Natural Elements of zoology, or, Natural history of animals / ed. by Reese elementsofzoolog00rees Year: 1849 496 ZOOLOGY. nida range over almost the whole globe ; and thus we may con- clude that the temperature of the parts at a distance from the equator was formerly higher than at present, and that it has gradually cooled down. Order III.—Holothurida. 868. In the last order of Echinodermata, the Holothurida. we find the characters of the class remarkably blended with those of Articulated animals. The body is not enveloped in a hard shell, but in an elastic skin,
Elements of zoology, or, Natural Elements of zoology, or, Natural history of animals / ed. by Reese elementsofzoolog00rees Year: 1849 496 ZOOLOGY. nida range over almost the whole globe ; and thus we may con- clude that the temperature of the parts at a distance from the equator was formerly higher than at present, and that it has gradually cooled down. Order III.—Holothurida. 868. In the last order of Echinodermata, the Holothurida. we find the characters of the class remarkably blended with those of Articulated animals. The body is not enveloped in a hard shell, but in an elastic skin, destitute of spines or prickles. It retains, in some species, the globular form, but in many it is very much prolonged, so as to be almost cylindrical, and thus to resemble that of the Worm tribes; and it is occasionally even marked by transverse bands, indicating a division into segments. Still, however, a distinctly radiated conformation may be seen around the mouth, and some of these animals look as if a star-fish were set as a head on the body of a large worm. In the general conformation of the internal organs they corre- spond with the Echinida, but they are in some respects more complex, and the respiratory organs are constructed upon the plan of those of the Articulata. They thus form a very inte- resting link of connection between the Radiated and Articulated sub-kingdoms. 869. The skin of most of the Holothurida is so very elastic, that they can change their size and form in a remarkable de- gree. They are capable, too, of swimming with considerable rapidity, and some of them crawl like slugs upon solid surfaces. Small species are occasionally found in British seas ; but in some tropical shores they are very abundant, and grow to the length of eighteen or twenty inches. They are sometimes eaten by the poor on the Neapolitan coast; but in the Malay archipelago they are regularly sought and conveyed to the Chinese market, where, under the name of trepang, they fetch a
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