224 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Syrskian organs. Syrski states that their greatest length is 430 milli- 

 meters [17 inches]. The eight specimens measured by Jacoby varied 

 in length from 310 to 480 [12i to 19 inches], and those measured by 

 Cattie from 270 to 380 millimeters [lOi to 15 inches]. In the males, 

 moreover, the distance between the nasal tubes is greater; the dorsal 

 fin is higher and broader ; the diameter of the eyea is noticeably larger, 

 comparing individuals of medium size. But these characteristics, in 

 my opinion, make it doubtful whether these fish were young specimens, 

 because in other fish the young may be recognized by the great devel- 

 opment of the fins and the comi^arative great size of the eyes. Jacoby 

 maintains that another sexual difference consists in the color, while 

 Cattie denies this and maintains, on the other hand, that the difl'erence 

 in the shape of the head is of greater importance — the female is said 

 to have a pointed and the male a round head. The umles are said to 

 form about 20 per cent of all the eels. 



Ifot less important are the results of Jacoby's observations regarding 

 the migration and the spawning season. The fact of the ascent of the 

 eels, called at Comacchio ^'- capillar i'''' (hair-like), and at the mouth of 

 the Arno ''■cieche^^ (blind eels), has long been known in Italy, and on it 

 is based one of our principal fishing industries. Thus from time imme- 

 morial the descent of the adult eels towards the sea has been explained 

 as being caused by their desire to spawn. There is no longer any doubt 

 that Jacoby found them on the coasts of the Adriatic by thousands ; 

 but he also found that these eels migrate in autumn when their stom 

 achs and intestines are entirely empty, and that those which remain 

 are nothing but barren females. Probably all the eels of our rivers, 

 ponds, and lakes are females, because the males stay in the sea near 

 the mouths of rivers, where they wait for the females to come to theu). 



The perfect development and the functions of the sexual organs seem 

 to be of very short duration ; in fact, the descent of the eels takes place 

 from the beginning of October till the end of December ; and already 

 in January, February, and March, as Mr. liichardi, of Tisa, iiiibniKs me, 

 the so-called " blind eels" ascend. It is possible, also, as Jacoby thinks, 

 that the reproducing individuals die after the actof generation, just as 

 Panizza always found the dead lampreys {Petromyzon marinus) void of 

 eggs and milt. 



There is lacking all decisive proof of the presence of spermatozoa in 

 the Syrskian organs; they cannot, therefore, with absolute certainty 

 be considered as testicles;* and the depth of the sea hides froui our 

 eyes the method of fecundation and the first development; but the 

 truth is nevertheless plain, and the idea of the hermaphrodism of the 

 eel may be considered as entirely exploded. 

 Pa VIA, Italy, Juhj 1, 1880. 



See article by J. A. Kyilcr iu F. C. Bulletin for 1885, p. 1. 



