File:Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct - for the use of schools and colleges (1870) (14802554263).jpg

Identifier: outlinesofcompar00agas (find matches)
Title: Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges
Year: 1870 (1870s)
Authors: Agassiz, Louis, 1807-1873 Gould, Augustus A. (Augustus Addison), 1805-1866 Wright, Thomas, 1809-1884
Subjects: Physiology, Comparative Zoology
Publisher: London : Bell & Daldy
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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TllE SKELETON OF ECHDSTODEEMS. 101 showing the skeleton of one of these lithophytes. The natu-ral size of the polypary is seen at fig. 69, and a magnified vie-*of one of the cells, with its rays, is given in fig. 70.) In the echinoderms, the test is brittle, and intimately united §/ with the soft parts. It is composed of numerous little plates,sometimes consolidated and immoveable, as in the sea-urchins,or combined, so as to allow of various motions, as in the star-fishes (fig. 36), and in the sea-lilies (figs. 72 and 73), whichuse their arms both for crawling and swimming.
Text Appearing After Image:
Fig. 71.—The test of an Echinus. On the right side are seen thespines and tubular suckers: on the left side, those parts have been re-moved, to show the surface of the test, composed of the ambulaeral ares,with the small plates, and poriferous avenues at their margins, and theinterambulacral areae, composed of the large polygonal plates. The platesof both area? being covered with tubercles, for supporting spines. (In the ECHrNiDj;, or sea urchins, the test is of a sphericalor pentagonal form, constructed of many series of calcareouspolygonal plates articulated together, and divided into twogroups, of which five form the ambulaeral areae, and five theinterambulacral arese, each area being composed of two columnsof plates (fig. 71 and 174, d, e). The ambulaeral alternatewith the interambulacral arese, and they are separated fromeach other by ten rows of small perforated plates, through theholes of which numerous tubular retractile suckers pass: the 102 THE SKELETON OF ECHIXODEEMS. mou

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