194 BULLETIN OF THE BUREAU OF FISHERIES. 



face is against the mesovarium. This position brings what has been termed the upper 



edge of the ovary downward, so that it is actually considerably lower than the supposed 



lower edge (fig. 2 d),so far as there is any edge. In other words, even the ovary is not 



platelike, but the supposed plate is folded in such a manner that it may be said in a 



general way to be boat-shaped with a decided list to starboard or port according to 



whether it is the left or right ovary. Posteriorly the exposed egg surface is usually 



proportionally wider and sometimes actually wider than at the anterior end. In fact, 



the anterior end is permanently covered to some extent by membrane, or to continue the 



boat simile, it is decked over forward (fig. 3). Furthermore, the ovigerous stroma, 



which has been stated to be arranged in vertical laminae, transversally and somewhat 



diagonally connects the two sides, dividing it into transverse compartments (figs. 3 B, 



4 jB5 and 5 B). 



OVIDUCTS OF SALMONID.*;. 



As relates to the vestigial or rudimentary' oviduct in the fonn of a narrow band to 

 which the previously quoted anatomists have referred, it is necessary to say that it 

 varies in extent according to the species and does not terminate as described by Rathke, 

 but, without close examination, in an immature, or spent, fish it might be so interpreted. 



In a silver salmon (O. kisutch), which was unripe* but approaching breeding condi- 

 tion, the lesser backward extent of the ovary resulted in a relatively longer band than was 

 evident in ripe fish, by which the general arrangement is more clearly defined. This band 

 (fig. 6 e) arises from the posterior end of the ovary whence backward it is an extension 

 of the ovarian covering and the mesovarium. The line of attachment of the mes- 

 ovarium (fig. 6 c) to the air bladder extends obliquely inward and backward toward 

 the median line of the air bladder until it attains a point near the termination of the 

 mesentery at the anterior end of the communicating aperture above the intestine 

 previously mentioned (fig. 6 w). Here the mesovarium, as such, apparently ends. 

 Fusing with the mesentery at a corresponding point- on the upper surface of the 

 intestine, the mesovarian membrane joins the membrane of the opposite side, form- 

 ing a single band, which is attached to and extends along the intestine backward. 

 The outer edge of this band, at the posterior end of the ovary, in unripe or imma- 

 ture fish at least, appears to fold over onto the band fonning a sort of hem to the edge 

 (fig. 6 /), later becoming the outer edge of the trough, which is supported by the lateral 

 walls of the narrow posterior portion of the abdominal caxdty. This outer edge pursues a 

 similar direction to the air-bladder attachment of the mesovarium to the point where the 

 mesentery and mesovarium terminate, whence it takes a course parallel with the middle or 

 line of attachment of the band to the intestine. Its outer edge remains free, and the 

 fold, though becoming narrower, is continued to within a short distance from the genital 

 pore, where it seems to vanish. The membranous band is deflected to either side and 

 becomes attached to the lateral abdominal wall (fig. 6 g). Thus from each ovary 

 a troughlike oviduct passage is formed as far as the termination of the mesentery 

 of the intestine, the two passages then merging into one which, not far from the outlet, 

 spreads out and joins the lateral wall on each side. This terminal structure would ap- 

 pear to be a reduced homologue of the so-called funnel described by Huxley in the case 

 of the smelt, 



1 Wicdersheim (Parker), 1897, p. 360. referring to these structures, says: "It is uncertain whether the latter is the primitive 

 arrangement amonc tcleosts, or whether the peritoneal funnels represent reduced oviducts." 



