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 Kays 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- 

 prey the ovarium is.a simple longitudinal mem- 

 branous plate, fig. 381, c, suspended by a fold 

 of the peritoneum fmesoarium) 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, b, 

 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 homotypal 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 peritoneal outlets, 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, 1 



in which the testis is single : 



the median cleft of the ovary 



of the Ammodyte is deeper 



than that of the testis, but the continuity of the two seemingly 



distinct glands is obvious at the upper and lower ends. In 

 1 xx. vol. iv. p. 13.3. prep. no. 2675, a. 



Renal and female organs : 

 Petromyzon. xx. 



382 



An ovarian fold of the Lamprey. 



