. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates -- Anatomy. GENERATIVE ORGANS. 313 The test is of Elasmobranchs is always paired and sym- metrical, and usually lies, supported by the mesorchium, towards. a -F-iG. 245.—FEMALE URINOGENITAL APPARATUS OF Protoptcrus annedcns. (From the ventral side, natural sue.) (After H. Ayers.) a,, vent ; , rectum ; ffg, apertures of ureters into cloaca ; L, L, lymphoid tissue ; Mg, Miillerian duct ; , abdominal aperture of latter ; N, kidney ; 0, ovary ; pi lung ; , postcaval vein ; , urinary bladder. the
. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates -- Anatomy. GENERATIVE ORGANS. 313 The test is of Elasmobranchs is always paired and sym- metrical, and usually lies, supported by the mesorchium, towards. a -F-iG. 245.—FEMALE URINOGENITAL APPARATUS OF Protoptcrus annedcns. (From the ventral side, natural sue.) (After H. Ayers.) a,, vent ; , rectum ; ffg, apertures of ureters into cloaca ; L, L, lymphoid tissue ; Mg, Miillerian duct ; , abdominal aperture of latter ; N, kidney ; 0, ovary ; pi lung ; , postcaval vein ; , urinary bladder. the anterior portion of the body-cavity. The relations of the vasa efferentia to the mesonephros have been already mentioned (comp. pp. 298 and 303, and Fig. 238s), and a somewhat similar arrangement is seen in Lepidosteus. Amongst Ganoids, the female organs of Lepidosteus 1 are formed on the same type as those of the Teleostei, while in cartilaginous Ganoids a more or less incomplete splitting of the segmental duct into a Miillerian and a a^ superficial resemblance to the amnion and chorion of Mammals, but these are both formed from the maternal tissues (T. J. Parker). 1 The cavity within the ovary of Lepidosteus is formed by a fold of peritoneum on either border of the-gland growing towards its fellow, and meeting in the middle line ; into this cavity the ova are shed3 and are carried to the exterior by an oviduct which is probably formed by continuations of these peritoneal folds behind the ovary. A similar mode of development of the oviduct possibly also obtains in 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 Wiedersheim, Robert, 1848-1923; Parker, W. N. (William Newton), d. 1923. London, New York, Macmillan
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