. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. FEMALE ORGANS OF FISHES. 571 381 discerned a fissure, which is the outlet of a blind sac, extending forward from the base of the clasper, beneath the muscles and skin, at the sides of the cloaca. The inner surface of the cavity is smooth, and lubricated by a fluid mucus: the attached vascular surface is richly supplied with vessels, especially with veins: in the Rays a glandular body adds its secretion to that of the surface of the cavity. § 107. Female Organs of Fishes.— The gradations of structure of the female organs
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. FEMALE ORGANS OF FISHES. 571 381 discerned a fissure, which is the outlet of a blind sac, extending forward from the base of the clasper, beneath the muscles and skin, at the sides of the cloaca. The inner surface of the cavity is smooth, and lubricated by a fluid mucus: the attached vascular surface is richly supplied with vessels, especially with veins: in the Rays a glandular body adds its secretion to that of the surface of the cavity. § 107. Female Organs of Fishes.— The gradations of structure of the female organs correspond very closely with those of the male. In the young Lam- jirey the ovarium is a simple longitudinal mem- branous plate, fig. 381, c, suspended by a fold of the peritoneum (mesoarium) along the under part of the vertebral column : it increases in breadth and thickness as the ova are developed in it, and still more so in length, being accom- modated to its locality by numerous folds, fig. .382. But no superadditions are made to this primitive structure: the ova, d, escape by rupture of their capsules into the abdomen, h, and are excluded by the peritoneal aperture, ib. I. In all other Fishes in which vasa deferentia are absent in the male, oviducts are absent in the female. But it does not always happen, where vasa deferentia are developed in the male, that the liomotypal ducts exist in the female: the Salmon is an example in which the ova are discharged by dehiscence into the abdominal cavity, and escape by jieritoneal oiitlets, as in the Eel and Lamprey. With this exception, the parallelism of the male and female organs is very close. Thus the ovarium is single in those bony Fishes, as the Perch, the Blenny, the Loach, and the Ammodyte,' in which the testis is single: the median cleft of the ovary of the Ammodyte is decider than that of the testis, but the continuity of the two seemino-ly distinct glands is obvious at the ujoper and lower ends. In ' XX. vol. iv. p.
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