. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. Fig. Posterior end ol body of a Beetle. (Pterostichus $) (after Steia). 8, 9, Dorsal plates 8' 9', ventral p'.atea; St, Btigma; A, anu3; G, genital opening. from one another by soft connecting membranes. They are com- posed of l^imple dorsal and ventral plates, which are also connected laterally by soft membranes. This structure of the abdomen, which contains the respiratory and genital organs, permits of its being dilated and contracted (respiratory movements, distension of the ovary). Very o
. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. Fig. Posterior end ol body of a Beetle. (Pterostichus $) (after Steia). 8, 9, Dorsal plates 8' 9', ventral p'.atea; St, Btigma; A, anu3; G, genital opening. from one another by soft connecting membranes. They are com- posed of l^imple dorsal and ventral plates, which are also connected laterally by soft membranes. This structure of the abdomen, which contains the respiratory and genital organs, permits of its being dilated and contracted (respiratory movements, distension of the ovary). Very often the posterior segments have a special struc- ture, owing to the various appendages which are con- :iected with the processes of copulation and of depo- sition of the eggs. The anus is usually placed on the last abdominal ring, while the generative open- ing which is separate from the anal aperture opens on the ventral surface of the preceding segment (fig. 437). Terminal appendages, such as jointed filaments, etc., are present on the anal segment. The ap- pendices genitalcs, forming the genital armature, are, on the con- trary, placed on the ventral side around the genital open- ing. Developed in the male as valves and in the female in the form of ovipositors, stings, etc., they arise from the imaginal discs (growths of the hypodermis), in the Hynienoptera and Orthop- tera on the eighth (first pair) and ninth (second pair) segments of the ab- domen (fig. 438). The ovipositors of the Diptera, on the other hand, are to be derived from the re- tracted posterior segments. Alimentary canal (figs. 439, 440).—The mouth, which is covered by the upper lip, usually leads into a narrow cesopha- gus, into the anterior portion of which, distinguished as the buccal 34. Pig. 438.—a, Hind end of abdo^ien or a young female Locusta with the protuberances of the ovipositor and the anal styles ; C and C, the internal and external protuberances of the penulti- mate; C"', the same of t
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanimals, bookyear1892
