76 THE CYPRINODONTS. 



dans les aiitres. Dans le male, les ureteres donnent dans la vessie fibreuse, 

 dans laquelle les laitances versent la liqueur seminale ; dans la femelle, c'est 

 a rextremite de I'oviducte. On doit se rappeler que, dans tous les autres 

 poissons, I'urine sort par un oi'ifice distinct de celui de I'ovaire ou des lai- 

 tances." " La communication entre la vessie et les sacs de la laitance est de 

 plus manifeste par la simple insufflation." "On pent done la considerer 

 comme une vessie urinaire, parce qu'elle recoit les ureteres, et en meme 

 temps comme une sorte de vesicule seminale, ou le canal deferent des tes- 

 ticules verse la laitance." Such is the description one might take from the 

 outside (see Plate VII. Fig. 11). A very different story is to be taken from 

 the interior (Fig. 12, 13). The receptacles for the urine and for the semen 

 are really distinct ; they are separate to the base of the first anal ray, where 

 their ducts join in a common tube. The muscular valve (x, Plate VII. Fig. 

 6, 11-13) at their junction represents the external openings on males of such 

 cyprinodonts as do not possess the added canal common to seminal and 

 urinal discharges. This common canal recalls the structure in similar use 

 among higher vertebrates. A structure almost identical, corresponding so 

 far as concerns the common tube on the anal fin, is seen on the females of 

 certain Funduli, F. heteroclUus for instance, on which ovaries and bladder 

 empty into a single tube at the base of the anal, the tube being extended 

 downward upon the first anal ray half or more of the length of the fin. The 

 growth of the tube in the young male of Anableps, also, presents much simi- 

 larity with that seen on the females of these Funduli. In the early stages, 

 sketched on Plate VII. Fig. 7-9, at different ages, the anal of these young 

 males shows close resemblances to that of the adult female in the other genus. 

 The advance from the ordinary in each case, before the male fin itself trans- 

 forms, is simply the extension of the tube downward, beyond the separate 

 ducts, along the anterior edge of the fin. A band of inelastic tissue {p) 

 crosses the neck of the bladder immediately behind the urinary chamber, 

 above the origin of the tube through which it empties, in such a manner 

 that by contraction of a muscle at each end of it, lying just outside of each 

 ventral fin, the urine is prevented from escape while the contents of the semi- 

 nal chamber are forced out through the valve (x) and the tube on the anal 

 fin (Plate VII. Fig. 6, 15). The great muscles (n) controlling the move- 

 ments of the anal of the male lie close behind and above the bladders and 

 no doubt also act as compressors. The arrangements for keeping the semen 

 separate from the urine are decidedly effectual. The bladder of the female, 



