. Comparative zoology, structural and systematic : for use in schools and colleges. Zoology; Anatomy, Comparative; Physiology, Comparative. ECHINODERMATA. 261 inverted, stemless Crinoids. The digestive sac is confined to the disk, and the raadreporic tubercle is Fig. 213. - Ophiocoma Russei, an Ophiuran; natural size. West Indies. Class III.—Echinoidea. The Sea-urchin is encased in a thin, hollow shell cov- ered with spines, and varying in shape from a sphere to a The mouth is underneath, and contains a dental apparatus more complicated than that of any other creat- ure. I
. Comparative zoology, structural and systematic : for use in schools and colleges. Zoology; Anatomy, Comparative; Physiology, Comparative. ECHINODERMATA. 261 inverted, stemless Crinoids. The digestive sac is confined to the disk, and the raadreporic tubercle is Fig. 213. - Ophiocoma Russei, an Ophiuran; natural size. West Indies. Class III.—Echinoidea. The Sea-urchin is encased in a thin, hollow shell cov- ered with spines, and varying in shape from a sphere to a The mouth is underneath, and contains a dental apparatus more complicated than that of any other creat- ure. It leads to a digestive tube, which extends spirally to the summit of the body. The spines are for burrow- ing and locomotion, and are moved by small muscles, each being articulated by ball-and-socket joint to a distinct tu- bercle. When stripped of its spines, the shell (or "test") is seen to be formed of a multitude of pentagonal plates, fitted together like a Five double rows of plates,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Orton, James, 1830-1877; Birge, E. A. (Edward Asahel), 1851-1950. New York : Harper & Bros.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1883
