262 Prof. G. B. Grassi. The Reproduction and 



Therefore, the hypothesis of Giinther that the Leptocephali are 

 abnormal larvas, incapable of further development, must be rejected. 

 All this is related by myself at length, with all historical details 

 which concern the question, in a large memoir which is about to 

 appear in the Journal edited by Professor Todaro. 



Until now all these facts have been unknown because normally 

 they can only be observed in the abysses of the sea at a depth of at 

 least 500 metres. Fortunately, along a part of the coast of Sicily 

 strong currents occur, which must be ascribed to the tide, producing 

 very large displacements of the water in the narrow Strait of Mes- 

 sina. I shall give further details concerning these currents in my 

 large memoir. In consequence of the strong currents, sometimes I 

 say sometimes, because there is no regularity, and one may have to 

 wait for a year without obtaining any material not only many 

 deep-sea fishes, but also all stages of the development of the Murae- 

 noids are met with in the surface-water. To these currents we owe 

 all the captures of Murcena Jielena with ripe eggs, which is in accord- 

 ance with what I had already argued from other facts, namely, that 

 the reproduction of the Muraenoids takes place at great depths of the 

 sea. 



Before I proceed to speak of the Common Eel, I must premise that 

 Dr. Kaffaele has described certain pelagic eggs as belonging to an 

 undetermined species, putting forward the suggestion that these 

 eggs belong to some Muraenoid. This matter has been investigated 

 by myself, and I have shown that the newly hatched larvae (called 

 " praa-larvae " by me) derived from these eggs have essentially the 

 character of Leptocephali. 



The life history of the Muraonoids, leaving aside for the present 

 the Common Eel, is as follows : Females can only mature in very 

 profound depths of the sea, that is to say, at least a depth of 500 

 metres. This fact I established by finding well-known deep-sea 

 fishes together with Leptocephali, ripe Muraenae, and quite ripe eels 

 {see below). The females of those species which do not live at this 

 depth must therefore migrate to it. The male, however, can mature 

 at a smaller depth, and therefore they migrate into the greater depth 

 when they are already mature. Fertilisation takes place at great 

 depths ; the eggs float in the water ; nevertheless they remain at a 

 great depth in the sea, and only exceptionally, for unknown reasons, 

 some of them mount to the surface. 



From the egg issues rapidly a pras-larva, which becomes a larva 

 (Leptocephalus) with the anus and the urinary opening near the tip 

 of the tail. The larva then becomes a hemi-larva, the two aper- 

 tures just named moving their position towards the anterior part of 

 the body, which becomes thickened and nearly round. By further 

 -change the hemi-larva assumes the definitive or adult form. The 



