. Echinoderms of Connecticut. Echinodermata. No. 19.] ECHINODERMS OF CONNECTICUT. 103 symmetrical, with both mouth and anus, and is known as a pluteus (Fig. 16). It bears absolutely no resemblance to the adult urchin. The free-swimming pluteus lives and feeds at the sur- face for a period of several weeks, the time depending some- what pn the temperature and other conditions, and varying in different species. In thiSj.time it may have been carried by cur- rents and tides to a considerable distance from its place of origin.. Fig. 17. Arbacia punctulata. Side view of young urchin immediately aft

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. Echinoderms of Connecticut. Echinodermata. No. 19.] ECHINODERMS OF CONNECTICUT. 103 symmetrical, with both mouth and anus, and is known as a pluteus (Fig. 16). It bears absolutely no resemblance to the adult urchin. The free-swimming pluteus lives and feeds at the sur- face for a period of several weeks, the time depending some- what pn the temperature and other conditions, and varying in different species. In thiSj.time it may have been carried by cur- rents and tides to a considerable distance from its place of origin.. Fig. 17. Arbacia punctulata. Side view of young urchin immediately after the metamorphosis. The spines re- maining from the pluteus are in process of absorption. (After Brook^.) When ready to assume the adult form, the pluteus settles to the bottom, absorbs its larval organs, and by a complicated meta- morphosis assumes the condition of a young urchin (Figs. 17 and 18). The young urchin differs from the adult in having the whole upper surface covered by the plates which will event- ually form only the periproct of the adult, and by the relatively enormous tube-feet. The animal is now radially symmetrical, and creeps about on the sea bottom after the manner of the adult urchin. It feeds upon diatoms and other minute organisms until.. 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 work.. Coe, Wesley Roswell, 1869-. Hartford, Printed for the State Geological and Natural History Survey