SEXUAL ORGANS. 255 



Cyclopterus, Pleuronectes, and been interpreted as such. In the 

 Sturgeon and Cyclostomi similar structures have not yet been met 

 with. 



SEXUAL ORGANS. 



THE organs of generation in Fishes present in general a very sim- 

 ple type of structure, and those of both sexes, at least in the Bony 

 Fishes and Cyclostomi, are formed upon a very analogous plan. It 

 may be here observed, that the opinion which was formerly held, that 

 regular hermaphrodites occurred among Fishes, is equally incorrect 

 with the assertion of genera of these animals existing in which the 

 male sex was wanting, and only individuals with female organs could 

 be found ; it is true that the female sex occurs in disproportionately 

 greater number than the male, as is the case also in many Inverte- 

 brate animals. 



The Ovaries of the Osseous Fishes are in general double, rarely 

 single, as in Perca fluviatilis, Cobitis, Blennius viviparus, though 

 even in these instances the separation is usually indicated. In the 

 majority of Fishes the ovaries consist of simple sacs formed of an ex- 

 ternal fibrous and internal mucous coat, which last usually presents 

 transverse, more rarely longitudinal folds, and sometimes also inter- 

 rupted papillae that are frequently clavate in form. Thus we find 

 longitudinal folds in Cottus, Gobius, and others, transverse in Pleu- 

 ronectes, Belone, and Gadus Callarias ; in Gadus Lota we meet with 

 shaggy papillae, in Blennius viviparus with tubercles. Upon these 

 projections of the mucous membrane the ova are developed in great 

 number ; those which are nearly mature hang from a pedicle, and 

 the less ripe have a shorter attachment ; both kinds are invested by 

 a thin membrane, by the dehiscence of which, or the rupture of the 

 pedicle, the ova when ripe fall into the cavity of the ovarium. In 

 the ovum itself we may distinguish a chorion, yelk, and a very large 

 and distinct germinal vesicle, provided with scattered germinal spots. 

 Each sacciform ovarium contracts posteriorly to form a short oviduct, 

 which very soon coalesces with its fellow into a common duct, that 

 opens usually within a depression, more rarely upon a tubercle, be- 

 hind the anus, and in front of the urinary aperture. Such is the 

 usual arrangement of these parts in the Osseous Fishes ; but in some 

 genera of the latter, as Salmo, Cobitis, and Taenia, in the Sturgeon 

 also, and in the Cyclostomi, the ovarium, instead of being sacciform, 

 is a flattened plate, from the lower or ventral surface of which folds 



