THE CYPRINODONTS. 75 



gestive of what obtain in young of Rivulus and Gambusia. As a whole the 

 circulation of the bag amounts to what in the adult would correspond to the 

 sinus emptying into the auricle, with the possible addition of a portion of 

 the ventral cutaneous vein. As worked out from the specimen at hand, a 

 vessel sent down from the cardinal just behind the gills at each side, passes 

 at the side of the heart, to the upper edge of the bag, where, as it extends 

 backward, it sends downward branches which branch again and again, then 

 converge and unite toward the point, near the middle of the lower surface of 

 the sac, at which they discharge their contents, with what has been added by 

 the papillce, into a vein or sinus (Plate VI. Fig. 1, 3, ss) that lies free from 

 and within or above the walls of the bag and runs forward and up to the 

 auricle, into which it discharges. Beside the two anterior supply vessels 

 another passes down from the main vessel above the bladder, below the verte- 

 hrx, to the left side of the vent below which it forks and sends a branch for- 

 ward along the upper edge of the bag at each side (Fig. 1, s', Fig. 7.) The 

 branches and branchlets of this vessel are similar to those of the anterior 

 portions of the bag, and they discharge into the same vessel (Plate VI. Fig. 

 1, 3, ss). At this stage the auricle lies below the ventricle (Fig. 12, 13), 

 As the bag atrophies the anterior vessels (s, in Fig. 12) at each side of the 

 auricle unite with the median {ss, of the same figure) to form the sinus 

 emptying into the auricle {s, in Fig. 10, 11). The lateral vessels of the 

 upper edge of the bag apparently give way to the ventral cutaneous vein. 

 The branchlets and the long median vessel (ss) are absorbed with the bag 

 itself In the change to the adult condition the auricle and ventricle change 

 places so that the latter eventually lies lower than the former, though not 

 directly below it. The heart of the young is outlined on Plate VI. Fig. 6, 

 12-14, and that of the adult in Fig. 10, 11. The bladder also undergoes 

 considerable changes in the young Anableps, as may be seen by comparison 

 of Plate VI. Fig. 1 {M), with Plate VII. Fig. 6, 11-15. 



Valenciennes, 1846, XVIII, 259, Atlas, pi. 539, has described and figured 

 the bladder of the male of Anableps, but from a very imperfect understand- 

 in"- of the structure. He ignores the muscular valve at the junction of the 

 seminal and urinary ducts (.r, in Plate VII. Fig. 6, 11-15), a structure which 

 represents the external openings of the ancestral form, and he says that 

 urine and semen are discharged into a common receptacle. " Les ureteres 

 sont deux longs tubes greles, attaches aux reins dans presque toute la lon- 

 gueur du viscere. lis se terminent dans ce poisson tout autrement que 



