File:Image from page 359 of "Comparative anatomy of vertebrates" (1912) (20047305684).jpg

Title: Comparative anatomy of vertebrates Identifier: comparativeanato00king Year: 1912 (1910s) Authors: Kingsley, J. S. (John Sterling), 1854-1929 Subjects: Anatomy, Comparative; Vertebrates -- Anatomy Publisher: Philadelphia, P. Blakiston's son & co. Contributing Library: MBLWHOI Library Digitizing Sponsor: MBLWHOI Library

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Text Appearing Before Image: 344 COMPARATIVE MORPHOLOGY OF VERTEBRATES. when the two are inserted in the cloaca the grooves unite to form a tube for the passage of the sperm. There is a large gland in the clasper but its relation to copulation and fertilization is unknown. In the snakes and lizards a second kind of structures occurs. In the young there are developed behind the vent a pair of sacs presenting the appearance of appendages. With farther growth these two hemipenes are withdrawn into a sac opening into the hinder side of

Text Appearing After Image: FIG. 343.—-Cloaca! region of adult turtle (Emys lutarid), after von Moller. The rectum and cloaca have been laid open from the dorsal surface and the urogenital sinus exposed. From the opening of the sinus into the cloaca a seminal groove extends along the ventral cloacal surface and can be cut off by a pair of folds (plica urorectales) from the cloacal cavity, av, anal vesicle; b, urinary bladder; o, opening of anal vesicle into cloaca; p, penis, exserted; pu, plicae urorectales; r, rectum; sg, seminal groove; ug, urogenital groove. the cloaca. Each hemipenis bears a spiral groove for the passage of the sperm. At the time of copulation these are everted through the anus (fig. 342). In all other aminotes the copulatory organs are formed from the same anlage. The lower anterior wall of the cloaca is largely con- cerned in this, the anterior cloacal lip being produced into a genital prominence (fig. 336) which can be traced in many forms as the clitoris of the female and the glans penis of the male. In the embryos of the higher mammals it is surrounded by a pair of integumental

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