Elementary text-book of zoology, general Elementary text-book of zoology, general part and special part: protozoa to insecta elementarytextbo00clau Year: 1892 Fig. 25' vidata ,—Larva of Jiurjlepta after Hallcz. probably the function of tactile organs. The mouth usually lies in the middle of tlie body, and leads into a wide and protrusible pharynx. The skin is often provided with glands, the secretion of which in certain land Planaria [Biixdium, Rhijnchodesmus) hardens to a fibrous web. They are almost always heimaplu'odite. The fresh-water forms possess a common generative opening, while in t
Elementary text-book of zoology, general Elementary text-book of zoology, general part and special part: protozoa to insecta elementarytextbo00clau Year: 1892 Fig. 25' vidata ,—Larva of Jiurjlepta after Hallcz. probably the function of tactile organs. The mouth usually lies in the middle of tlie body, and leads into a wide and protrusible pharynx. The skin is often provided with glands, the secretion of which in certain land Planaria [Biixdium, Rhijnchodesmus) hardens to a fibrous web. They are almost always heimaplu'odite. The fresh-water forms possess a common generative opening, while in the marine forms the generative openings are usu- ally separate (fig. 250). In the latter case a separate vitellarium is absent. In some marine forms development takes place with metamorphosis, as is shown by the larva discovered by J. MUller, which possessed six provisional finger-like ciliated lobes (fig. 251). In the fresh-water Pianarians develop- ment is direct. The cocoon, when laid, contains four to six small eggs. At the close of segmentation there is developed a layer of cells, which is said to split into two layers, an upper or animal layer, from Avhich are derived the body wall and muscular system, and a lower or vegetative, from which the alimentary canal is formed. The marine Dendroccela fre- quently deposit their eggs in the form of broad bands. 1. Monogonopora Stimps. Den- droccela with single sexual opening. The land and fresh-water Planaria be- long to this group. Fam. Planariadse. The body is of a long, oval, flattened shape, und is often provided with lobed processes, more rarely with ten- tacles, and, as a rule, with two eyes, which are provided with lenses, rianaria O. Fr. Miillcr, two eyes, no tentacles. Fl. torra, M. Sch. (divided by O. Schmidt into h/f/7/hris, 2)ohjchroa, and torva) (fig. ). PZ. dioica Clap., with separate sexes. Dcndroceelum Oerst. Distinguished by the possession of lobed processes on the head, also by the presence of a copulatory
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