Metamorphosis of the Common Eel. 267 



nourishment whatever. The resumption of growth was accompanied 

 by a resumption of feeding. Unfortunately, I had no other indi- 

 viduals of this stage. 



The stage which I now pass on to describe can be obtained during 

 the winter in the sea. I have never found them at the mouths of 

 rivers. The length varies from 54 to 73 mm. Most individuals 

 measured about 65 mm. The body is relatively longer than in the 

 elver. It is also relatively deeper, as in Leptocephalus. We are 

 reminded of Leptocephalus also by the pigment of the eye, the 

 vitreous transparency of the body, the swim-bladder being indis- 

 tinguishable in the living animal, and the absence of all larval pig- 

 mentation. The blood is slightly coloured, and the bile is already 

 green. Slight pigmentation can be seen along the central nervous 

 system, and at the middle part of the caudal fin. This commence- 

 ment of the definitive or adult pigmentation in the regions named 

 before it occurs in any other part is also seen in other Muraenoids. 

 The definitive teeth are very minute, and few in number. The 

 intestine contains no food. After what I had observed in the other 

 Mursenoids, the simple observation of the barely indicated teeth, 

 and of the absence of aliment in the gut, would have been sufficient 

 to convince me that the stage now under notice must be preceded by 

 a Leptocephalus phase. Indeed, if we did not admit such a preceding 

 history, we could not understand how this little fish could have 

 attained such a size without acquiring well developed teeth, and with- 

 out nourishing itself. 



In conclusion, no one would hesitate, even not knowing Lepto- 

 cephalus brevirostris, to refer the stage now under discussion to a 

 Mureeiioid about to complete its Leptocephalus metamorphosis, were 

 it not for the fact that there has been so much question concerning 

 the reproduction of the Common Eel, and that so many capable 

 observers have failed in dealing with it, that every new observation 

 is received with scepticism. The stage of which I am now speaking, 

 in the hands of a pure systematist, would probably be described as a 

 Helmicthys, a genus established for certain forms of Leptocephali far 

 advanced in transformation. 



The next forms to which I have to refer are captured in the course 

 of migration from the sea into fresh water. When kept in an 

 aquarium they assume the characters of the elver, diminishing more 

 or less in volume, and without nourishing themselves. The elvers 

 of the Common Eel can present themselves in stages differing 

 little from that last described, as well as in a form which has 

 already developed the full pigmentation of the adult. Even those 

 which most resemble the preceding stage always have a character 

 which distinguishes them easily, namely, the presence of definitive 

 pigment, more or less superficially placed on the head, and not to be 



