450 THE EEL FAMILT. 



observed in individuals which have not yet migrated to deep 

 water, with the exception of the eels of the Roman cloacae \ 

 The abysses of the sea are the spawning-places of the common 

 eel: its eggs float in the sea- water. In developing from the 

 egg it undergoes a metamorphosis, that is to say, passes through 

 a toothed prse-larval stage, then a larval form denominated 

 Leptocephalus hrevirostris. What length of time this develop- 

 ment requires is very difficult to establish. So far we have 

 only the following data : (1) Anguilla vulgaris migrates 

 to the sea from the month of October to the month of 

 January ; (2) the currents, such as those of Messina, throw 

 up, from the abysses of the sea, specimens which, from 

 the commencement of November to the end of July, are 

 observed to be more advanced in development than at other 

 times, but not yet arrived at total maturity ; (3) eggs, which 

 according to every probability belong to the common eel, are 

 found in the sea from the month of August to that of January 

 inclusive ; (4) the Leptocephalus hrevirostris abounds from 

 February to September. As to the other months we are in 

 some uncertainty, because during them our only natural fisher- 

 man, the short sun-fish {Orthagoriscus mala), appears very 

 rarely ; (-5) I am inclined to believe that the elvers ascending 

 our rivers are already one year of age, and I have observed that 

 in an aquarium specimens of L. hrevirostris can transform 

 themselves into young elvers in one month's time.' 



The part of this curious life-history in which there is most 

 room for doubt is the question as to the identity and habitat of 

 the eggs of the eel. 



The Congee. {Conger vulgaris, Cuv.) 



This fish is a very near ally of the eel, and its reproductive 

 organs are of a similar type. There is however an important 

 difference in the habits of the two species ; thus whilst the eel 



' The large-eyed eels are familiar to us in the pond on the Isle of May, and 

 occasionally elsewhere, so that Grassi's remark that this increase 'finds its 

 physiological explanation in the circumstance that the eel matures in the 

 depths of the sea' opens up some interesting questions. 



