. A manual of zoology. i68 MANUAL OF ZOOLOGY more than five arms the number is inconstant. The pro- portions borne by the arms to the central disc also vary greatly in different kinds, the arms being in many instances relatively longer, in many relatively shorter than Asterias, and in the latter case (Figs. 91 and 92) the central disc is cor- respondingly increased in extent. In some extreme instances of this modification the starfish assumes the form of a five-. Fig. 92. — Anthenea. View of ventral surface. From New Zealand. (After Sladen.) angled disc, in which the arms are represented merel
. A manual of zoology. i68 MANUAL OF ZOOLOGY more than five arms the number is inconstant. The pro- portions borne by the arms to the central disc also vary greatly in different kinds, the arms being in many instances relatively longer, in many relatively shorter than Asterias, and in the latter case (Figs. 91 and 92) the central disc is cor- respondingly increased in extent. In some extreme instances of this modification the starfish assumes the form of a five-. Fig. 92. — Anthenea. View of ventral surface. From New Zealand. (After Sladen.) angled disc, in which the arms are represented merely by the angles. In all cases the arms are hollow, each containing a prolongation of the body-cavity containing the caeca; and in all the mouth is in the centre of the ventral surface, and narrow ambulacral grooves run out from it in a radiating manner to the extremities of the arms. In some starfishes there are but two rows of tube-feet in each arm. An anus. 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 Parker, T. Jeffery (Thomas Jeffery), 1850-1897; Haswell, William A. (William Aitcheson), 1854-1925. New York, The Macmillan Company; London, Macmillan & Co. ,Ltd.
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