Elementary text-book of zoology, general part and special part: protozoa to insecta . elementarytextbo00clau Year: 1892 262 C(£Li:XlERATA. Fig. 201. — Cyd'ppe, Been from the apical pole. S, Sagittal plan?; T, transverse plane ; R, swimnung plates; Gf, gastro-vascular system. an oesophageal tube and a gastro-vascular canal system. Two lateral tentacles, which can be retracted into pouches, are often present. The Ctenophora possess a shape which can in all cases be reduced to a sphere. They are radially symmetrical free-swim- ming Coilenterata of gelatinous consistence. The body is often bil
Elementary text-book of zoology, general part and special part: protozoa to insecta . elementarytextbo00clau Year: 1892 262 C(£Li:XlERATA. Fig. 201. — Cyd'ppe, Been from the apical pole. S, Sagittal plan?; T, transverse plane ; R, swimnung plates; Gf, gastro-vascular system. an oesophageal tube and a gastro-vascular canal system. Two lateral tentacles, which can be retracted into pouches, are often present. The Ctenophora possess a shape which can in all cases be reduced to a sphere. They are radially symmetrical free-swim- ming Coilenterata of gelatinous consistence. The body is often bilaterally compressed, so that it is possible to distinguish two planes passing through the long axis at right angles to one an- other ; these arethesa^t^ irt^planeand the transverse plane, and are analogous to the median (longitudinal vertical), and lateral (longitudinal horizontal) planes of bilaterally symmetrical animals (fig. 201). The arrangement of the internal organs bears a relation to these two planes. All parts of the body which occur in pairs, as the two tentacles, the gastric canals, the hepatic bands of the stomach, and the vessels which give oingin to the eight lateral canals, all lie in the transverse plane, while the sagittal plane coincides with the longer axis of the oesophageal (gastric) tube (whence also called the gastric plane), the two so- called pol r-fields, and the terminal vessels of the infundibulum. The infundibulum is so compressed that its longest diameter falls in the lateral plane, which on this account is sometimes called the infundibular plane. Since these two planes divide the body into halves, which correspond with one another, and since there is no division into dorsal and ventral surfaces, the arrangement of the body may be said to be bi-radially symmetrical, but cannot be called
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