198 BULLETIN OF THE BUREAU OF FISHERIES. 



observed). Both ovaries are ventrally convex from side to side, and concave above, 

 Aus forming a broad, more or less triangular, continuous groove in which anteriorly the 

 stomach lies. The intestine, at first above the stomach, finally lies in the grooves of the 

 left and right ovaries. These grooves are formed by the left ovary curving over so that 

 its so-called lower edge is in contact, or nearly so, with the dorsal surface of the abdom- 

 inal cavity on the right side, and the left ovary curving in like maimer in the reverse 

 direction. 



Except in shape and relative position the ovaries are much like those of the salmonids 

 previously described. They are nearly covered by a very delicate membrane which is so 

 thin that it is easily broken or rubbed off, so that one may be easily deceived into 

 believing that there is no membrane and that the eggs are free in the abdominal cavity. 



The mesovarium (fig. 9 c) arises near the lateral edge of the air bladder, and, in 

 the case of the anterior ovary, its line of attachment gradually passes obliquely inward 

 to its attachment to the intestine. The mesovarium of the posterior ovary has a 

 proportionally longer intestinal attachment. 



As in the Salmonidse, the dorsal mesentery (fig. 10 /) ends some distance from 

 the posterior end of the intestine (fig. 10 w), and the mesovarial membranes unite to 

 form the floor of the common opening above the intestine. The outer edges continue 

 attached to the lateral walls of the abdominal cavity (figs. 9 g and 10 g). Thus the mes- 

 ovarian membranes, originating on th3 outer side of each ovary and deflecting to 

 the abdominal walls, form the floors of the respective oviducts, while the peritoneum 

 of the air bladder, the abdominal walls, and the mesentery form the other boundaries. 



As in the case of the Salmonidse, the portion of each ovary uninvested with adherent 

 membrane consists of a narrow dorsal area which is tipped in against the mesovarium. 

 In these passages, formed by the investing membranes, the ova pass backward into the 

 oviducts. If they are set free into the abdominal cavity, there appears to be no con- 

 ceivable way by which they can be extruded. The smelt appears to have no ventral 

 mesentery, unless a close adhesion to the ventral or abdominal surface near the vent 

 is such. 



As previously stated, the gravid ovaries are situated one behind the other and 

 almost entirely fill the abdominal cavity, save the comparatively small space occupied 

 by other viscera. Before the ova of the left ovary have entered the oviduct, the gravid 

 right ovary presses the left oviducal membrane (fig. 9 g) against the air bladder 

 and left abdominal wall. 



The ova of the right ovary ripen, enter the oviduct, and are deposited first. As 

 the right ovary is emptied and its oviduct (fig. 10 g) is filled, the ova of the left 

 ovary enter its oviduct and the empty and collapsed right ovary is compressed between 

 the distended left oviduct and the right abdominal wall. The left ovary and its dis- 

 tended oviduct, together with the distended right oviduct, then have the appearance 

 of a single mass of eggs, but, by careful manipulation, a longitudinal line of separation 

 may be detected. As the right oviduct is emptied the left becomes entirely filled and 

 with the remaining ova in the left ovary has the appearance of a single continuous 

 ovary. Probably this was the condition which deceived Bloch, causing him to think 

 that the smelt had but one ovary. When both ovaries are emptied and collapsed, the 

 left is considerably anterior to the right and may have the appearance as described by 

 Huxley; that is, a semioval plate, laminated on the outside and having a marginal 

 membrane of about one-third its width. 



