446 THE EEL FAMILY. 



What becomes of the eels after spawning ? According to 

 several writers they never return to fresh water, but dis- 

 appear altogether. The view of Siebold that the eel, like 

 the lamprey, dies after the reproductive act, has been accepted 

 by Jacoby, Cattie, Benecke and others. The ovaries of the 

 migrating eel are very immature, and if the swarms of elvers, 

 which ascend the rivers in May, are produced from the eels 

 which migrated in the preceding autumn, the reproductive 

 organs must arrive at a ripe condition with extraordinary 

 rapidity. It is considered probable that the excessively rapid 

 development of their organs of generation exhausts them to 

 such a degree that they die a physiological death soon after 

 they have spawned. 



Amongst the numerous conjectures with regard to the 

 origin of eels, there is one of early date which bids fair to 

 have a sound basis of truth. There is a small group of peculiar 

 little fishes, known as Leptocephali, and by various naturalists 

 these have been supposed to be larval forms of members of 

 the eel-family, or Murcenidce. The recent work of two Italian 

 naturalists, Grassi 1 and Calandruccio, points to the conclusion 

 that one of these Leptocepliali, namely L. brevirostris, is trans- 

 formed into the eel by a remarkable metamorphosis, which 

 involves a reduction in length besides other changes. The 

 key to this curious history was the discovery of the life- 

 history of the conger (see Conger), and the Italian observers 

 have followed nearly the whole process of metamorphosis, as 

 they have in the conger, and have obtained a sufficient number 

 of transitional forms to identify the eel, its pra>larva, and its 

 larva. 



Kaup long ago gave this diagnostic account of Lepto- 

 cephalus brevirostris : No dots ; fourteen teeth in each jaw ; 

 small slender tail supported by visible rays ; eyes black ; total 

 length 3'15 inches. Locality, Messina. 



Up till now this species of Leptocephalus with a single 

 exception referred to below has not been found anywhere but 

 at Messina, and the reason for this peculiar fact is probably 



1 Proceed. R. S. vol. 60, p. 260, Dec. 1896, and Q. J. H. Sc. Nov. 1896, 

 p. 371. 



