. A manual of zoology. Zoology. Fig. 283. Fig. 2S4. Fig. 283.—Three stages in the development of the coelom and water-vascular system (after Bury and McBride). a, ampulla; b, stone canal; c', c'-, left and right ccelom sacs; d, hind gut with anus; h\ h'-, left and right (rudimentary) hydrocoele sac; he, common anlage of hydrocccle and co^loni; m, stomach; 5, stomodeum and mouth. Fig. 284.—Formation of Ophiuran from the pluteus larva (after MuUer, from Korshelt-Heider). Class I. Asteroidea (Starfish). Two parts can be recognized in the body of a starfish, a central disc and the arms, usually fi
. A manual of zoology. Zoology. Fig. 283. Fig. 2S4. Fig. 283.—Three stages in the development of the coelom and water-vascular system (after Bury and McBride). a, ampulla; b, stone canal; c', c'-, left and right ccelom sacs; d, hind gut with anus; h\ h'-, left and right (rudimentary) hydrocoele sac; he, common anlage of hydrocccle and co^loni; m, stomach; 5, stomodeum and mouth. Fig. 284.—Formation of Ophiuran from the pluteus larva (after MuUer, from Korshelt-Heider). Class I. Asteroidea (Starfish). Two parts can be recognized in the body of a starfish, a central disc and the arms, usually five in number, which radiate from it (fig. 290). The relations in which these stand to each other vary between two extremes. In many starfish the arms play the chief role and the disc appears as only their united proximal ends (fig. 285). On the other hand, the disc may increase at the expense of the arms, so that they form merely the angles of a pentagonal disc (fig. 286). In both arms and disc two surfaces are recognized, oral and aboral, which pass into each other, usually without a sharp margin. In the normal position the oral side is downwards and has the mouth in the centre and radiating from it to the tips of the arms the five ambulacral grooves. Near the centre of the aboral surface is the anus (when not degenerate) and excentric from it in an interradius is the madreporite (in many-armed species two to sixteen interradii may have madreporites).. 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 Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929, ed. and tr. New York, H. Holt
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
