The Apodes, or Eel-like Fishes 145 
of the eel was recognized, also by an Italian naturalist, Dr. 
Syrski, in small individuals of the species, and a previous idea 
that the eel was hermaphroditic thereby dispelled. The sexual 
differences are correlated with external ones, and generally the 
males and females, when adult, can be told apart. Jacoby 
testifies that he examined large numbers with a view to solve 
this question. The most important differences relate to (1) 
size; (2) form of the snout; (3) color; (4) dorsal fin; and 
(5) size of the eyes. (1) The males rarely attain a length of 
more than seventeen to nineteen inches, while adult females 
are generally much larger; (2) the snout in the male is attenu- 
ated and rather pointed, while in the female it is comparatively 
broad and blunt; (3) the male is of a deep darkish green, or 
often a deep black with a shining luster and a whitish 
belly, while the female has a clearer color, usually of a greenish 
hue on the back and yellowish on the belly; (4) the dorsal fin 
is lower and less developed in the male than in the female; and 
(s) the eye of the male is large and that of the female, as a rule, 
comparatively small. These characters, however, do not always 
hold good. Jacoby remarked that ‘special reference having 
been paid to the height and narrowness of the dorsal fin, much 
success has been met with in picking out, in the fish-market 
of Trieste, the eels which possessed the organ of Syrski (that 
is, the male organ); absolute certainty, however, in recog- 
nizing them cannot be guaranteed. If one is searching among 
living eels with no characters in mind,—with the exception of 
the first, that of length,—he will find in every ten eels, on an 
average, eight females and two with the supposed male organ, 
but if the selection is made with a careful reference to all these 
marks of difference, the proportion changes, and out of every 
ten examples about eight will be found with the supposed 
male organ.’ 
“ According to Herr Benecke, ‘it may be assumed with the 
greatest safety that the eel lays its eggs like most other fish, 
and that, like the lamprey, it spawns only once and then dies. 
All the eggs of a female show the same degree of maturity, 
while in the fish which spawn every year, besides the large 
eggs which are ready to be deposited at the next spawning 
period, there exist very many of much smaller size, which are 
II—10 
