. A text-book of invertebrate morphology. Invertebrates. 88 INVERTEBRATE MORPHOLOGY. ous stout spines occur. Some of the hydranths are typical trophopolyps (Fig. 44, tp) with filiform tentacles and a mouth, but among them are gonopolyps {gp) with short-knobbed tentacles below which the medusa-buds arise. In addition there are also towards the periphery of the colony much longer slender hydranths without a mouth and like the gono-. FiG. 44.—Portion of Colony of Mydractinia echinata (adapted from figure by HiNCKSI. gp = gonopolyp. mp = offensive polyp. tp = trophopolyp. polyps in having short-kn
. A text-book of invertebrate morphology. Invertebrates. 88 INVERTEBRATE MORPHOLOGY. ous stout spines occur. Some of the hydranths are typical trophopolyps (Fig. 44, tp) with filiform tentacles and a mouth, but among them are gonopolyps {gp) with short-knobbed tentacles below which the medusa-buds arise. In addition there are also towards the periphery of the colony much longer slender hydranths without a mouth and like the gono-. FiG. 44.—Portion of Colony of Mydractinia echinata (adapted from figure by HiNCKSI. gp = gonopolyp. mp = offensive polyp. tp = trophopolyp. polyps in having short-knobbed tentacles, but differing from them in their greater length and in never producing medusa- buds. Finally, in a European species of the genus a fourth exceedingly long polyp {mp), destitute of both mouth and tentacles, but furnished at its free end with numerous nemato- cysts,. occurs. These third and fourth varieties of polyp probably are offensive and defensive in function, procuring food for the colony and warding off some predatory enemies. The AnthomedussB, as the medusa forms are termed, have much deeper bells than the Leptomedusse, and differ from the latter in that the sense-organs are light-percipient in their. 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 McMurrich, J. Playfair (James Playfair), 1859-1939. New York, H. Holt and Company
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