MEMBRANES, OVARIES, AND OVIDUCTS OF SALMONOIDS. I97 



These backward extensions of the ovaries are formed by the maturing and enlarging 

 Ova filling the previously crowded intcrlamina spaces at the posterior end of the ovary 



(fig- 3). thus stretching it longitudinally. 



PERITONEAL MEMBRANES, OVARIES, AND OVIDUCTS OF COREGONID.ffi. 



A number of sp)ecimens of each of the genera Coregonus and Leucichthys were 

 examined. 



The arrangement of the visceral organs was similar to that of the Salmonidae, but no 

 ventral mesentery was observed. The ovaries and oviducts were much as in Salmonidae. 



OVARIES, OVARIAN MEMBRANES, AND OVIDUCTS OF SMELTS. 



As has been seen, according to Huxley, the smelts were supposed to have free 

 ovaries and oviducal funnels, while the salmonids were stated to have free ovaries and 

 only narrow bands, or vestigial homologues of oviducts. My examination of many smelts 

 reveals that, while Huxley was correct concerning the oviducal structures, his interpre- 

 tation of the ovary was not in accord with all of the facts. He probably accurately 

 described what he saw under certain limited conditions. I previoush' remarked that at 

 no time in their development can the ovaries be said to be exactly the same as at any 

 other time. This is particularly true as concerns the ovaries of the smelt (Osmerus 

 mordax). If the ovary of a spent fish, or one from which the eggs have been removed 

 or washed out, as Huxley stated of his example, is examined, the condition is likelv to 

 be as represented by Huxley. The ovary then is in a collapsed, flabby condition, or 

 more or less shrunken state. When the ovaries are full-grown, just before spa\^•ning time, 

 but before any ova have been discharged into the oviducts, the}' exhibit an entirely 

 different appearance. As described of Salmonidae, the air bladder is attached to each 

 side of the dorsal portion of the abdominal cavity and is covered by the closely adhering 

 peritoneal membrane, in which the mesovarium of each ovary originates. 



Posteriorly the intestine is dorsally situated, and the mesentery is there so narrow 

 that the intestine appears to be almost adherent to the peritoneum of the air bladder. 



Huxley correctly described the anterior origin of the oviducal membrane at the 

 posterior end of each ovary and the relative situation of each ovar3^ the right or smaller 

 ovary being posterior to the left or larger ovary. 



The oviducal membranes, as in the case of the salmonids, finally unite in a common 

 channel above the intestine. Both of these oviducal membranes, when not containing 

 ova, posteriori}', lie against the membrane of the air bladder which forms the roof of the 

 so-called funnel. 



The gravid ovaries practically fill all the space in the abdominal cavity not occupied 

 by other viscera. Upon opening the fish from throat to vent along the median line of 

 the belly and laying the lateral walls aside, at first glance there appears to be one single 

 mass of eggs in front of which is the liver; posteriorly a small portion of the intestine 

 may be visible. The greater portion of the egg mass is the anteriorly situated left ovary 

 which extends from the liver to some distance beyond the base of the ventral fins (fig. 

 80). Closely juxtaposed to the posterior end of the left ovary is the right ovary 

 (fig. 9 h) which extends nearly to the vent. The dividing line, which is often difficult 

 to discern, beginning perhaps a little in advance of the ventral fins, extends ob- 

 liquely from the right side (left as observed) backward to the left side (right as 



