. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. Trm3ELLABIA—DENDROCCELA. 315. 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 ope
. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. Trm3ELLABIA—DENDROCCELA. 315. 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 organ i)laccd in a special sheat
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanimals, bookyear1892
