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; 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. i 
~ 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- 
