. Elementary text-book of zoology. Zoology. ABDOMEN AND ITS APPENDAGES. st. from one another by soft connecting membranes. They are coin- posed of simple 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- nected with the processes of copulation and of depo- sition of the eggs. The anu
. Elementary text-book of zoology. Zoology. ABDOMEN AND ITS APPENDAGES. st. from one another by soft connecting membranes. They are coin- posed of simple 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- nected 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 (tig. 437). Terminal appendages, such as jointed filaments, etc., are present on the anal segment. The ap- /»-inllces genitales, 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 imagiiial discs (growths of the hypodermis), in the Hymenoptera and Orthop- FIG. Posterior end of body of a Beetle. (Pterostichits $) (after Stein). 8, 9, Dorsal plates 8' 9', ventral plates; St, stigma; A, anus; G, genital 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; Sedgwick, Adam, 1854-1913; Sinclair, F. G. (Frederick Granville), b. 1858. New York : Macmillan
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
