. Zoology : for students and general readers . Zoology. 133 ZOOLOGY. aster Philippii Gray (Figs. 84 and 85), from the latter island, certain of the ambulacral plates are greatly expanded and depressed " so as to form four deep, thin-walled oral cups, sinking into and encroaching upon the cavity of the test, and forming very efficient protective ; The spines are so arranged that a kind of covered passage leads from the ovarial opening into the marsupium, and along this passage the eggs, which are very large (a millimetre in diameter) are passed and arranged in rows, each egg
. Zoology : for students and general readers . Zoology. 133 ZOOLOGY. aster Philippii Gray (Figs. 84 and 85), from the latter island, certain of the ambulacral plates are greatly expanded and depressed " so as to form four deep, thin-walled oral cups, sinking into and encroaching upon the cavity of the test, and forming very efficient protective ; The spines are so arranged that a kind of covered passage leads from the ovarial opening into the marsupium, and along this passage the eggs, which are very large (a millimetre in diameter) are passed and arranged in rows, each egg being kept in place by two or three spines bending over it. Here the eggs develop, and the embryos, after the calcareous. Fig. 85.—Marsupium of Hemiaster Philippii, contsdmag eggp. Much magnified.— From Wyville-Tliompsou's Voyage of ttie Clialleuger. plates once begin to develop, rapidly assume the parent form; when they leave the marsupium they are about two and a half millimetres long. In Cidaris nutrix Wy ville-Tliompson the eggs are protected in a sort of tent by certain spines near the mouth. Here the young develop without a meta- morphosis. The allies of these forms in the Northern At- lantic are either known or supposed to be metabolous; and Sir "Wyville-Thompson states that no free-swimming Echi- noderm larvte (pluteus, etc.) were seen by the Challenger Expedition in the Southern 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 Packard, A. S. (Alpheus Spring), 1839-1905. New York : Henry Holt
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectzoology, bookyear1879
