REPRODUCTION AND METAMORPHOSIS OF COMMON EEL. 3883 
obtained pre-larvee which had only forty-four abdominal 
myomeres. I endeavoured for two years in vain to study 
these eggs at the Zoological Station of Naples. I found only 
a few of them, and these died prematurely. 
In another point my researches have yielded a very inte- 
resting result. As a result of the observations of Petersen, 
we know now that the common eel develops a bridal colora- 
tion or “ mating habit,” which is chiefly characterised by the 
silver pigment without trace of yellow, and by the more or 
less black colour of the pectoral fin, and finally by the large 
eyes. Petersen inferred that this was the bridal coloration 
from the circumstance that the individuals exhibiting it 
had the genital organs largely developed, had ceased to take 
nourishment, and were migrating to the sea. Here Petersen’s 
observations cease and mine begin. The same currents at 
Messina which bring us the Leptocephali bring us also many 
specimens of the common eel, all of which exhibit the silver 
coloration. Not a few of them present the characters de- 
scribed by Petersen in an exaggerated condition,—that is to 
say, the eyes are larger and nearly round instead of elliptical, 
whilst the pectoral fins are of an intense black. It is worth 
noting that in a certain number of them the anterior margin 
of the gill-slit is intensely black, a character which I have 
never observed in eels which had not yet migrated to the sea, 
and which is wanting in the figures and in the originals sent to 
me by Petersen himself. Undoubtedly the most important of 
these changes is that of the increase of the diameter of the eye, 
because it finds its physiological explanation in the circumstance 
that the eel matures in the depths of the sea. That, as a 
matter of fact, eels dredged from the bottom of the sea have 
larger eyes than one ever finds in fresh-water eels I have 
proved by many comparative measurements, made between eels 
dredged from the sea bottom and others which had not yet 
passed into the deep waters of the sea. Thus, for instance, in 
a male eel taken from the Messina currents, and having a total 
length of 343 cm., the eye had a diameter, both vertical and 
transversal, of 9 mm. and in another eel of 334 cm. the same 
