378 RECENT REPORTS OF FISHERY AUTHORITIES. 



reproductive organs of both males and females are in a much more 

 advanced condition. The silver eels emigrate from the rivers to the sea 

 in summer and autumn, and are caught in traps, the mouths of which 

 are set to face up-stream. In winter all the eels caught are yellow 

 eels. 



Petersen points out that, in consequence of the above relations 

 between the different kinds of eels in closed waters or rivers, 

 where all the silver eels can be caught as they emigrate to the 

 sea, the yellow eels should not be taken at other times, but allowed 

 to remain until they become silver eels of larger size and greater 

 value. 



In confirmation of Petersen's views, and in order to complete the 

 history, we may add the following quotation from Grassi's most recent 

 paper in the Frocccdmgs of the Royal Society*: — 



" In another point my researches have yielded a very interesting 

 result. As a result of the observations of Petersen, we know now that 

 the common eel develops a bridal coloration 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 described 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 34i cm., 



* Proceedings Hoy. Soc, vol. Ix. No. 363. Sec also Quart. Journ. Micr. Set., New 

 Series, vol. xxxix. part 3. 



