I90 BULLETIN OF THE BUREAU OF FISHERIES. 



parallel with that of the mesentery and a little distance from it. The ovary, described 

 as a broad, thin plate, was stated to have its inner surface covered by the peritoneum, 

 which is continued over the ventral edge, ending about a third or fourth of the height 

 of the outer face by a well-defined margin and its outer face "to give rise to a great 

 number of ovigerous lamellae of broadly triangular form, which are disposed transversely 

 to the length of the organ and perpendicularly to the body." Huxley went on to say 

 that superficially the ovary appears to be laminated only above the reflected membrane, 

 but that transverse section revealed that the ovigerous laminse pass under the band to 

 the ventral wall and that their outer edges are attached to the band. 



In the Salmonidae, then, according to both Rathke and Huxley, ovigerous laminae 

 without peritoneal covering occupy the outer surface of the pendent mesovarial fold, 

 thus constituting the ovary, from which as they ripen and burst from their investing 

 follicles, the ova fall into the abdominal cavity. As will be seen later, the foregoing 

 observations pertain to only one stage, that of a collapsed and retracted ovary. 



Prior to Huxley's description of the oviduct of the smelt, no salmonoid was sup- 

 posed to have such a structure. In the smelt, according to Huxley, the mesovarial fold 

 continues backward from the posterior end of the ovary to the oviducal apertures, 

 while laterally it passes into the peritoneal lining of the lateral wall of the abdomen, 

 ending in a free concave edge immediately behind and on the outer side of the posterior 

 extremity of the ovary. It thus forms the ventral boundary of a passage which opens 

 in front by a wide ostium into the abdominal cavity. As the posterior end of the right 

 ovary lies very far behind that of the left ovary, it follows, Huxley says, that the right 

 ostium is equally far behind the left. The mesentery, he continues, terminates by a 

 free posteriorly concave edge just opposite the level of the posterior end of the right 

 ovary; and, behind this free concave' edge of the mesentery, the left and right passages 

 unite in a short but wide common chamber which opens externally in the middle line 

 behind the anus and in front of the urinary outlet. 



It appears that it must be to this structure in the smelt that all subsequent writers 

 refer when mentioning oviducts of Salmonidae, many regarding the smelt as a member 

 of this family. 



This idea that the salmonoids have no oviducts and that the ova are deposited 

 free in the abdominal cavity has been handed down to the present day in all literature 

 pertaining to the subject. Owen (1866) said that the salmon is an example in which 

 the ova are discharged by dehiscence into the abdominal cavity and escape by the peri- 

 toneal outlets, as in the eel and lamprey, and that the free surface of the stroma of the 

 ova is exposed. 



Gegenbaur (1878) said that in the Salmonidae the eggs are passed into the abdominal 

 cavity and are evacuated through the abdominal pore. 



Giinther (1880) wrote that in some families of fishes the ovaries are without closed 

 covering and without oviduct, as in Salmonidae, Galaxidae, Notopteridae, Muraenidee, 

 and others. He stated that the surface of such an open ovary — as, for instance, that of 

 the salmon — is transversely plaited, the ova being developed in capsules in the stroma 

 of the lamina; after rupture of the capsules, the mature ova drop into the abdominal 

 cavity and are expelled by the porus genitalis. 



Day (1887) makes practically the same statement, saying that the ovaries are sym- 

 metrical organs and destitute of a closed covering, while their internal surface is lined 



