Smithsonian miscellaneous collections . we note the occurrence of similar abdominal proc-esses in other unrelated larvae, the interpretation of any of them asprimitive styli becomes doubtful. The aquatic larva of the gyrinidbeetle Dineutcs (fig. 10 B), for example, has a pair of long, taperinglateral filaments arising from each of the first eight abdominal seg-ments and two pairs from the ninth segment. The single filamentsare supported on lobes of the body (fig. 9 H) that lie in a line above 58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 122 the level of the pleural plates (PI) of the thorax.
Smithsonian miscellaneous collections . we note the occurrence of similar abdominal proc-esses in other unrelated larvae, the interpretation of any of them asprimitive styli becomes doubtful. The aquatic larva of the gyrinidbeetle Dineutcs (fig. 10 B), for example, has a pair of long, taperinglateral filaments arising from each of the first eight abdominal seg-ments and two pairs from the ninth segment. The single filamentsare supported on lobes of the body (fig. 9 H) that lie in a line above 58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 122 the level of the pleural plates (PI) of the thorax. Each lobe is crossedinternally by two layers of vertical muscle fibers (I) enclosing a largetrachea between them (J,K,7Va) that runs out into the filament. Thefilament itself is movable by two antagonistic muscles, one mesal, theother lateral, attached on its base. Then there is the curious termi-tophilous tineid caterpillar, Plastopolypus divisus (fig. 10C), firstdescribed by Silvestri (1920), which has long, slender, multiarticulate. Fig. 10.—Examples of unrelated holometabolous larvae with lateral appendicu-lar organs on the abdomen. A, Sialis sp. Megaloptera. B, Dineutcs sp. Coleoptera-Gyrinidae. C, Plasto-polypus divisus Silv. Lepidoptera-Tineidae (from Hollande, Cachon, and Vail-lant, 1951). D, Nymphula maculalis Clemens, Lepidoptera-Nymphulidae (fromWelch, 1916). processes projecting from the sides of the first seven segments of theabdomen. These appendicular structures have been shown by Hol-lande, Cachon, and Vaillant (1951) to be sensory and not exudatoryorgans, since they are covered with innervated setae and contain noglandular tissue; but these writers, and also Silvestri, find that eachappendage is movable by a muscle inserted within its base. Must we,therefore, interpret all these structures as representative of thysa-nuran styli ? Hollande, Cachon, and Vaillant contend that the abdomi-nal appendages of the Plastopolypus caterpillar are merely secondaryadaptati
Size: 1934px × 1292px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1860, bookidsmiths, booksubjectscience
