. Elements of zoölogy. Zoology. 20 COMPOUND HYDRO IDS, Developme?it of Discophora.—They multiply by eggs that are deposited in the autumn, and are at first spheri- cal, quickly changing to a pear-shape, and attaching them- selves to rocks or weed. Now, tentacles appear (Fig. 17, 1), varying in number from eight to twenty-four, and after eight- een months the pear divides off into disks until we have a pile of scalloped saucers one upon another (2). The high- est one dies, while all the rest break off and swim away, lit- tle jelly-fishes, that in time grow into the gigantic Cyanea or others, as
. Elements of zoölogy. Zoology. 20 COMPOUND HYDRO IDS, Developme?it of Discophora.—They multiply by eggs that are deposited in the autumn, and are at first spheri- cal, quickly changing to a pear-shape, and attaching them- selves to rocks or weed. Now, tentacles appear (Fig. 17, 1), varying in number from eight to twenty-four, and after eight- een months the pear divides off into disks until we have a pile of scalloped saucers one upon another (2). The high- est one dies, while all the rest break off and swim away, lit- tle jelly-fishes, that in time grow into the gigantic Cyanea or others, as the case may be. Value.—They form the food of some whales and fishes. Note.—The gigantic Cyanea af- fords a home under its curtains for numbers of fishes and several crus- taceans, while in its mouth-folds lives a long, tapering sea-anemone {Bicidiumparasiticum), that in many cases mimics in color that of its protector. Order III. Siphonopho- ra.—These are the most beau- tiful of the Hydroids, and are rarely seen in the North. They are free-swimming colo- nies. The Portuguese man- o'-war, or Physalia (Fig. 19), is a mere bubble, seemingly of the finest satin, that floats upon the surface. From the upper portion rises at will a fluted membrane, colored with delicate tints of pink, that is used as a sail; from the low-. Fig. 19.—Portuguese man-o'-war, Physalia 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 Holder, Charles Frederick, 1851-1915; Holder, Joseph Bassett, 1824-1888, joint author. New York : D. Appleton and company
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
