— 148 — 



that Dareste's ' conclusion in 1873, does not seem unexpected: "Je me crois donc fondé à 

 admettre que le Leptocephahis Spalanzanii est le jeune âge du Congre, et que, par consé- 

 quent il doit cesser de figurer dans les catalogues ichthyologiques à titre d'epèce distincte 

 .... Je pense qu'il en est de même des autres Leptocéphales, que, par conséquent, le 

 genre Leptocéphale de l'ordre des Helmichthydae doit être rayé des cadres zoologiques." 



In 1870 Gill's view regarding the sameness of Leptocephahis Morrisii and the 

 conger was accepted by the celebrated English ichthyologist A. Günther^, who however 

 brought forward the peculiar theory, that though Leptocephahis was indeed derived 

 from the conger (which he concludes from the resemblance between them in many reg- 

 ards, e.g., number of vertebrae) yet it was not its normally developed offspring. Günther 

 still retains this theory in his "Introduction to the Study of Fishes" published in 1880. 

 He imagines that the Leptocephali are the eel larvae which are borne by accidental causes 

 up to the surface and out from the coasts to the open sea, and that they thus develop 

 abnormally, so that they are unable to complete their development and become young 

 eels. Günther mentions several features which might be in favour of his theory. One- 

 of the most important is that he had found small Conger young of only 4^/2 inches in 

 length, whilst Leptocepalus Morrisii is usually longer, which is not usually the case 

 with earlier stages, most species of fish and other animals increasing regularly in size 

 during development. Briefly put Günther's view is, that the Leptocephali are the larvae 

 of eels, which by reason of abnormal external conditions have developed abnormally and 

 are therefore unable to complete their development and become young eels, like the larvae 

 which have the opportunity to develop under normal external conditions, but which however 

 are unknown. Günther's conception of the Leptocephali as abnormal, overdeveloped eel 

 larvae how extraordinary it may seem has however won supporters. Thus, the Italian 

 ichthyologist C.Bellottis, who investigated the Leptocephali of the Messina Straits, read 

 Günther's theory in connection with the fact that quite unusual hydrographie conditions 

 (whirlpools) prevail in the Messina Straits, and believed that if the Leptocephali were ab- 

 normally developed eel larvae this was to be ascribed just to the varying hydrographie 

 conditions in the Messina Straits. It should be remembered in this connection that the 

 Straits of Messina was the only place (at least in Europe) where the Leptocephali had 

 been found regularly and in quantities, and it is thus not difficult to understand how 

 Bellotti with Günther's theory in mind could arrive at this standpoint. 



At the beginning of the eighties of last century the problem of the Leptocephali had 

 thus become so involved that quite a different method of investigation had to be devised 

 for its solution especially as the matter was brought to a standstill by the theory advanced 



1 Camille Dareste, Note sur le leptocéphale de Spallanzani (Journal de Zoologie par P. Gervais, tome 2, 

 année 1873, p. 295 — gg, 1873, as also in the Comptes Rendus for the same year). It may be mentioned that 

 E. MoREAU, the author of "Poissons de la France" states in that work vol. Ill, p. 568, that he had come to 

 the result after anatomical investigation, that Lepiocephalus Morrisii was the young form of Couger, but he 

 does not refer to any treatise in which he had published this result. He reports however that Dareste, who 

 had been permitted to examine his (MoREAu's) preparations had appropriated and published the results in the 

 paper mentioned above. Concerning this I am naturally unable to judge. 



2 A. GÜNTHER, Catalogue of the fishes in the British Museum, vol. VIII, p. 136 — 138. London, 1870, 



3 C. Bellotti, Note ittiologiche. Osservazioni fatti sulla collezione ittiologica del. Civico Museo di storia 

 naturale, in Milano. VII. I Leptocefali del Mare di Messina. Atti della Societa Italiana di scienzc naturali, 

 vol. XXVI. Anno 1883, Milano 1883. 



