442 Wyman's Observations on 



Valenciennes has given a very full and detailed descrip- 

 tion of the modified ventral fin, which serves the function of 

 an external male organ, and of its connection with the 

 excretory tubes of the testis ; yet, in some respects, the 

 specimens which I have examined differ from his description. 

 In these the anal fin (Fig. 9) consisted of two portions, 

 one of which forms a conical-shaped body resting on an 

 enlarged base and attached to or forming the anterior edge 

 of the fin, and is covered with scales as far as its termi- 

 nation j its anterior half is colored black at the base, but 

 the whole of it is so colored nearer the apex ; at the extremity 

 is the genito-urinary opening, as described by Valenciennes. 

 Behind the genital portion, and partially imbedded in it, is 

 the true ventral fin, containing seven or eight rays parallel 

 to the genital tube, the posterior being the shortest, and 

 about one half as long as the whole fin. In a larger and 

 adult male, measuring about seven inches in length, the 

 genital portion of the fin has become very much longer and 

 stouter in consequence of the development of muscular 

 fibres in its interior. The genital opening, which, in the 

 preceding specimens, was not at the extremity of the fin, 

 has now become terminal, the fin rays have become propor- 

 tionally shorter and so closely applied to the posterior face 

 of the genital portion as to be detected with difficulty. In the 

 figure of the fin, given in the Histoire Naturelle des Poissons, 

 the artist has erroneously represented the fin rays as if they 

 were attached by their base to the side of the genital tube ; 

 when in reality they are attached to the under side of the 

 abdomen, and are parallel to the genital tube, but partially 

 imbedded in it. 



Valenciennes inclines to the belief that the fin in question 

 could not be used as an intromittent organ in consequence 

 of the scales and fin rays pointing in such a manner as to 

 prove an obstacle. This objection applies less to the adult 

 than the younger specimens, since the fin rays have become 

 much less prominent ; but when the structure of the intro- 



