BULLETIN OF THE UNITED STATES FISH COMMISSION 



93 



green, or often a very deep black upon the back and always a more per- 

 ceptible metallic luster upon the sides (I, once in a while, found eels 

 covered all over with a brownish tint, always possessing the organ 

 of Syrski), usually exhibiting also a white color ui)on 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 

 organ 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 in- 

 terest ; column a gives the total length of the eel ; b the breadth of 

 the snout between the nostrils ; c the breadth of the snout between the 

 eyes; d the length of the snout from the center of the eye to its tip; 

 € the average measurement of the eyes ; / the length of the head to 

 the gill-opening ; g the height of the dorsal fins, all the measurements 

 being given in millimeters. 



According to the distinguishing marks which have been given, 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 ; absolute cer- 

 tainty in recognizing them cannot, however, be guaranteed. If one is 

 searching among living eels with no characters in mind with the excep- 

 tion of the first — that of length — he will find in every ten eels, on an 

 average, eight females, and two with the sujiposed male organ; but, if 

 the selection is made with a careful reference to all these marks of difier- 

 ence, the proportion changes, and out of every ten examples about eight 

 will be found with the supi)osed male organ. 



For another excellent discussion with figures of the characters of 

 male and female eels, the reader is referred to a translation of an article 

 by S. Th. Cattie, in the Proceedings of the U. S. National Museum, vol. 

 iii, pp. 280-4. 



