. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. Fig. 277.—Filidium (after E. Metschnikoff). a, free swimming larva vnih invaginated cavity ; b, later stage, helmet-shaped; E, E' the tvfO pairs of ectodermal invaginations; D, alimentary canal. cocoon. Some forms, as Prosorochmus Claparedli and Tetrastemma ohscurum, are viviparous. Some of the Anopla develop with a metamorphosis. The larva is ciliated and m ay pass through a free - swimming stage, in which case it is known as the Fili- dium, or it may be without such a stage {Type ofDesor). In both
. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. Fig. 277.—Filidium (after E. Metschnikoff). a, free swimming larva vnih invaginated cavity ; b, later stage, helmet-shaped; E, E' the tvfO pairs of ectodermal invaginations; D, alimentary canal. cocoon. Some forms, as Prosorochmus Claparedli and Tetrastemma ohscurum, are viviparous. Some of the Anopla develop with a metamorphosis. The larva is ciliated and m ay pass through a free - swimming stage, in which case it is known as the Fili- dium, or it may be without such a stage {Type ofDesor). In both cases the perfect worm is deve- loped within the skin of the ciliated larva. 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 segmentation is regular, and results in the formation of a spherical ciliated em- bryo, which is hatched and becomes a free-swimming larva; the archenteron is then formed by invagina- tion ; and at the side of the embryo, opposite the blasto- pore, a long flagellum is developed (fig. 277, a). On each side of the mouth a broad lobe grows out, the edges of which are fringed with cilia (fig. 277, h). Two pairs of invaginations of the ectoderm now make their appear-. Pio. 278.—Later stage of Pxhilaim, with tuft of cilio and enclosed Nemertme (after Butschh), Oe, oesophagus; D, alimentary canal ; wftm, 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; Metcalf Collection (North Carolina State University). NCRS. London, Swan Sonnenschein
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanimals, bookyear1892
