THE EEL FAMILY. 457 



pelagic environment may, under such abnormal conditions, 

 become leptocephaline in appearance. As recently as in 1880 

 he still upheld the same theory in his Introduction to tie X///f/// 

 of Fishes. His main point appears to be the fact that young 

 congers are found, which are considerably smaller than many 

 specimens of Leptocephalas morrisii ; this is, to some extent, 

 accounted for by a reduction in size during the metamorphosis. 



At as recent a date as 10 years ago, Professor Delage of 

 Paris, made the announcement that he had succeeded in 

 following the whole transformation from L&ptocephalus to 

 conger. Two young Leptocephali were captured in February, 

 and one of these was kept in confinement till September. The 

 earliest changes commenced in May and consisted in the 

 appearance of a black pigment in the skin and of a thin silvery 

 rudiment of the air-bladder. The general shape of the body 

 became more cylindrical, and the head more blunt and 

 square, and these changes proceeded little by little till in July 

 the ribbon-shaped transparent larva was completely trans- 

 formed into a little conger of 3'5 inches having most of the 

 adult characters. It is much to be regretted that the dimen- 

 sions of the Leptocephalus were not given, so that in this case 

 there is no evidence of the reduction in size which is said 

 to take place. 



This discovery, though for some time unsupported, has now 

 been amply verified by two Italian observers, Professor Grassi 

 and Dr Calandruccio, to whose work reference has already been 

 made (see 'the Eel'). They worked at Messina, at which 

 place, on account of the currents mentioned, Leptocephali are 

 found in great abundance. Apart from other important results, 

 they have shown that the two forms Leptocephalus morrisii and 

 L. punctatus are stages in the life-history of the conger. They 

 suggest that the scarcity of Leptocephali upon British coasts is 

 due to the fact that they may bury themselves in the sand or 

 mud. We are now in a position to trace the details of what is 

 known of the development. As a whole, the Leptocephali are 

 elongated, ribbon-like fishes with a very small head, pellucid 

 and silvery, no trace of reproductive organs, no air-bladder, no 

 ribs and hardly any ossifications. 



