TENTH ANNUAL MEETING. 99 
The most important, writes Jacoby, is (1) the difference in the 
size and length of the animal. Syrski states that the largest eels 
found by him with the supposed male organ measured about r7 
inches, 430™™. I have, however, found specimens with this 
organ at Trieste and in Comacchio which measured 17 to 19 
inches, 450 to 480™™, AJ] the eels which exceeded this size, for 
instance those which were over 3 feet in length, 1™, many of 
them growing to the thickness of the arm of a strong man, have 
been hitherto found to be females. The other recognizable ex- 
ternal character in the female are (2) a much broader tip of the 
snout in comparison with the small, either attenuated or short 
and sharply pointed, snout of the eel with the supposed male 
organ; also (3) a clearer coloration in the female, usually of a 
greenish hue on the back, and yellowish or yellow upon the 
belly, while the others have a deep darkish green, or often a very 
deep black upon the back and always a more perceptible metal- 
lic luster upon the sides (I, once in a while, found eels covered 
all over with a brownish tint, always possessing the organ of 
yrski), usually exhibiting also a white color upon the belly. 
~ In addition (4) there is an important external character in the 
height of the dorsal fin; all females have these fins much higher 
and broader than the eels of the same size which possess the 
. supposed male organ. Finally (5) there is a character, which is 
not always a safe one, in the greater diameter of the eye in the 
eels with the supposed male organ. Eels with quite small eyes 
are almost always found to be females; eels with the organs of 
Syrski usually have comparatively large eyes, yet female eels 
with quite large eyes are not unusual. 
The following proportional measurements, the average results 
of the study of a great number of eels measured by me, will be 
of general interest; column a gives the total length of the eel; 4 
the breadth of the snout between the nostrils; ¢ the breadth of 
the snout between the eyes; d the length of the snout from the 
center of the eye to its tip; e the average measurement of the 
eyes; f the length of the head to the gill-opening; g the height 
of the dorsal fins, all the measurements being given in mille- 
meters. 
