. The microscope and its revelations. at FIG. 655.—Structure of the chela of Mo-naxonid Sponges: 1, tridentate anisochelafrom in front; la, from the side; 2, la,front and side views of a palmate isocliela ;/, /, tubercle; at, at, anterior tooth orpalm ; U, It, lateral tooth or palm ; s, shaft;/, timbria. (After Ridley and Dendy.) single axis, but the growth from the point of origin may be on either side, when we have two-rayed or diactinal megaloscleres, or it may extend in one direction only, when the scleres are said to be monactinal. In the Calcispongise there are three axes and three
. The microscope and its revelations. at FIG. 655.—Structure of the chela of Mo-naxonid Sponges: 1, tridentate anisochelafrom in front; la, from the side; 2, la,front and side views of a palmate isocliela ;/, /, tubercle; at, at, anterior tooth orpalm ; U, It, lateral tooth or palm ; s, shaft;/, timbria. (After Ridley and Dendy.) single axis, but the growth from the point of origin may be on either side, when we have two-rayed or diactinal megaloscleres, or it may extend in one direction only, when the scleres are said to be monactinal. In the Calcispongise there are three axes and three rays : but in some sponges, such as Teiiuss flower-basket, the growth is along both directions of the axes, so that while there are three axes there are six rays, or the spicules are hexactiiiellid. In others, such as Ceodia and the Lithistid Sponges, there are four axes, whence such forms are called tetraxonid. 1 A minute account of the various forms of spicules contained in Sponges is givenby Mr. Bowerbank in his first memoir On
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