. Elementary text-book of zoology. Zoology. FIG. 277.—Pilidium (after E. Metschnikoff). «, free swimming larva with invaginated cavity ; b, later stage, helmet-shaped; E, E1 the two pairs of ectodermal invaginations; D, alimentary canal. The Pilidium larva is helmet-shaped, and was formerly described as the species of a supposed independent genus, Pilidium, and presents many analogies to the Echinoderm larva. In the case of the Pilidium, the R Am D. segmentation is regular, and results in the formation of a spherical ciliated em- bryo, which is hatched and becomes a free-swimming larva; the ar
. Elementary text-book of zoology. Zoology. FIG. 277.—Pilidium (after E. Metschnikoff). «, free swimming larva with invaginated cavity ; b, later stage, helmet-shaped; E, E1 the two pairs of ectodermal invaginations; D, alimentary canal. The Pilidium larva is helmet-shaped, and was formerly described as the species of a supposed independent genus, Pilidium, and presents many analogies to the Echinoderm larva. In the case of the Pilidium, the R Am D. segmentation is regular, and results in the formation of a spherical ciliated em- bryo, which is hatched and becomes a free-swimming larva; the archenteroii is then formed by invagina- tion; and at the side of the embryo, opposite the blasto- pore, a long nagellum is developed (tig. 277, a). On each side of the mouth a broad lobe grows out, the edges of which are fringed with cilia (tig. 277, b). Two pairs of invaginations of the ectoderm now make their appear- Oe FIG. 278.—Later stage of Pilidiuw, with tuft of cilia and enclosed Neruertine (after Biitschli); Oe, oesophagus ; D, alimentary canal ; Am, amnion; -R, rudimentary proboscis of the Nemertine; So, lateral 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 Claus, Carl, 1835-1899; Sedgwick, Adam, 1854-1913; Sinclair, F. G. (Frederick Granville), b. 1858. New York : Macmillan
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
