Smithsonian miscellaneous collections . the endophallic musclesmust produce movements of the endophallic walls other than those con-cerned with the opening and closing of the gonopore and the com-pression of the ejaculatory sac described above. The male genitalia of the Tetrigidae, by comparison with theacridid organs, are not only very simple in structure, but, as observed 70 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, 94 by Walker (1922), they are surprisingly unlike those of the Acridi-dae. The phallus of Tettigidea lateralis (fig. 27 D) consists of alow ovate elevation on the floor of the g
Smithsonian miscellaneous collections . the endophallic musclesmust produce movements of the endophallic walls other than those con-cerned with the opening and closing of the gonopore and the com-pression of the ejaculatory sac described above. The male genitalia of the Tetrigidae, by comparison with theacridid organs, are not only very simple in structure, but, as observed 70 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, 94 by Walker (1922), they are surprisingly unlike those of the Acridi-dae. The phallus of Tettigidea lateralis (fig. 27 D) consists of alow ovate elevation on the floor of the genital chamber beneath thepallial valve (C). Sclerites in the lateral walls of the organ convergeand unite anteriorly in a median process armed with small the lateral plates is a large, widely open, membranous cavity,into the bottom of which the ejaculatory duct opens anteriorly (D,Gpr). The posterior wall of the cavity is directly continuous withthe inner membranous fold of the pallium {Pal). The ejaculatory PlVlv ..Phi. C / ^^^^^ D Fig. 2y.—Abdomen and male genitalia of Tettigidea lateralis (Tetrigidae). A, terminal part of abdomen. B, dorsal view of pallial valve (PlVlv) andanterior process of phallic organ. C, lateral view of ninth sternum and pallialvalve, with phallic organ exposed beneath the latter. D, the phallic organ, dorsalview, with base of inner pallial fold. duct has strongly muscular walls, and groups of muscle fibers arisingon the phallic sclerites are inserted on its terminal part. Coition isprobably effected by evagination of the endophallic sac. Accordingto Walker the external phallic plates of the tetrigid organ representthe epiphallus ( pseudosternite ) of the Acrididae; but the attach-ment of the ejaculatory muscles upon them would make it seem moreprobable that they are external representatives of the invaginatedendophallic plates of the Acrididae. These plates, Walker himselfcontends, are derived from external plates or processes ( para
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