MEMBRANES, OVARIES, AND OVIDUCTS OF SALMONOIDS. igi 



with stroma and transversely plaited. Here, he said, the development of the eggs takes 

 place, each of which is invested by a fine membrane, by which they hang suspended to 

 the ovary, the length of the pedicle decreasing as the egg augments in size. But as the 

 ovaries are destitute of oviducts it necessarily occurs, he continues, that when the invest- 

 ing membrane bursts, the ovum falls into the abdominal cavity, from whence it is extruded 

 through the abdominal pore. 



Jordan and Gilbert (1882) and Jordan and Evermann (1896) make similar state- 

 ments: "Ova falling into the cavity of the abdomen before exclusion." 



In discussing the brown trout {Salmo jario) as an example of "subclass III Teleos- 

 tomi" Parker and Haswell (1897) state that the ovaries extend the full length of the 

 abdominal cavity and are covered with peritoneum on their inner or mesial faces only, 

 and that, when ripe, the numerous ova are discharged from their outer faces into the 

 abdominal cavity. They then go on to say that there are no oviducts, but that the 

 anterior wall of the urogenital sinus is pierced by a pair of genital pores through which 

 the ova make their way to the exterior. 



A previously cited authority (Wiedersheim, Parker, 1897) wrote that the ovary of 

 some teleosts is solid and that the ova are shed into the body cavity. The oviducts of 

 the smelt (Osmerus) and capelin (Mallotus) were referred to as peritoneal funnels having 

 open coelomic apertures close to the ovaries, into which the ova pass. In the case of 

 other Salmonidae, the Mursenidae, and Cobitis, it was stated that these peritoneal funnels 

 are shorter and even absent, the ova then being shed into the urogenital sinus through 

 paired or single genital pores. 



After describing the genital structures of the Salmonidae, Bridge (1904) states that 

 in all instances the eggs are set free from the ovaries into the coelome, whence they escape 

 through the peritoneal funnels or genital pores. The foregoing statements reveal the 

 influence of Rathke and Huxley upon all subsequent interpretations of the structures. 



The only teleosts besides Salmonidae mentioned by Rathke as possessing no o\'iducts 

 were two species of loach {Cobitis harbatida and C. UEnia) and the eel. Regarding these 

 Huxley savs that in Cobitis barbatula the single ovary has an oviduct of the same charac- 

 ter as other Cyprinoid fishes, but that he had not examined C. tcrnia, about which, in 

 other parts of his memoir, Rathke's statements were full and precise. 



Inasmuch as one of the species of the loach was found to have an oviduct, it is quite 

 possible that the other has also. If such is the case, according to Rathke, the only 

 supposedly o^^ductless species, besides the Salmonidae, left without such a duct is the 

 eel. However, a few other fishes have since been stated to be oviductless. 



The salmonoids, according to the authorities mentioned, appear to occupy almost' 

 a unique place among teleosts; but in the discussion which follows I hope to show that 

 their position is not as anomalous as from the foregoing it would seem to be. 



OBSERVATIONS UPON OVARIES AND OVARIAN MEMBRANES OF SALMONID^. 



The two ovaries in each of the salmonoids which I have examined are never exactly 

 symmetrical in form or of the same length. They have a general primary shape which 

 is maintained, but in their growth and enlargement such modifications of shape and posi- 

 tion as occur are largely determined by contiguous internal organs and the abdominal 

 walls. Each ovary is suspended by a membrane (fig. 2 c) originating in the dorsal 



