MEMBRANES, OVARIES, AND OVIDUCTS OF SALMONOIDS. 



193 



peritoneum at the side of the air bladder. This membrane covers the surface of the 

 ovary which faces the longitudinal axis of the body cavity. From its posterior end a 

 membranous band, which is a continuation of the mesovarium and ovarian covering 

 extends toward the posterior end of the abdominal cavity. Up to this point the condi- 

 tions are as stated by the anatomists previously cited. 



An immature ovary shows that its membrane not only covers the mesial or inward 

 surface as described, but envelops the entire organ. The edge of the membrane, which 

 was stated to mark the termination of the covering at or near the lower margin of a 



B'B 



Fig. 3. — Upper view of left ovary, with most of ova removed, showing cross septa and membrane extending up over the 

 forward end. A , mesovarium from which ovary is turned downward to show upper view. 



Fig. 4. — Dorsal view of a section of same ovary as in fig. 3 from the region of B, BB representing the same cross septum as 

 B in figs. 3 and 5. Some ova have been removed, others are shown still in the foUicles. ,4 . mesovarium. 



Fig. 5. — Cross septum (B) in upright position. In natural position, mesovarium (.4 ) would incline to right, and upper edge 

 of septeum (B) to left. Impressions of ova shown in septum. 



Figs. 3 to 5 drawn by Mrs. Effie B. Decker. 



platelike ovary, passes up over the outer surface and is in contact with the membrane 

 of the inward surface. At this time the ovary has much the same general external ap- 

 pearance as that of the other isospondylous teleosts. At a later period, beginning at the 

 posterior end of the ovary, the edge of the membrane of the outer surface to some extent 

 parts from the membrane of the inward surface, leaving a narrow area of ova without 

 attached membranous cover. The area thus uncovered gradually widens and extends 

 forward as the ovary increases in size. Even at maturity the egg surface is to a certain 

 extent infolded in membrane (fig, 2 a), due to the fact that the suspensory meso- 

 varium does not hang vertically but, from its origin at the side of the air bladder slants 

 inward toward the axis of the body cavity, and the egg surface is tipped over so that its 



