MR. T. SOUTHWELL ON THE REPRODUCTION OF THE COMMON EEL. 2G5 
described by Yarrell (183G), under the name of Leptocephalus 
morrisii, from an Anglesea specimen. Many other specimens have 
since been taken in our seas, but this is the only species met with 
here. These Leptocephali have been by others regarded as the 
larval forms of various kinds of marine fish, or as representing an 
arrested form of development taking place at a very early period 
of their life before the characters of the adult form were 
developed. It may suffice to say, that our Leptocephalus morridi 
has been satisfactorily proved to be the larva of the Conger Eel 
{Conger vulgaris), and that the first result of the researches of 
Professor Grassi is to lead him to suppress the whole family 
of Leptocephaluhe, “ the various forms of which are, in fact, the 
normal larvae of the various Muraenoids.” The number of 
supposed species had been greatly increased by the casual 
observance of the larva of the same species at different periods of 
its development. 
We may now turn to the discoveries made by Dr. Grassi with 
regard to the development of Anguilla vulgaris. It has been 
pointed out that the great difficulty in pursuing observations 
with regard to the reproduction of this fish arises from the 
fact that the process takes place far from land and in the abysses 
of the sea. “Fortunately," says Dr. Grassi, “along a part of the 
coast of Sicily strong currents occur, which must be ascribed to 
tide, producing very large displacements of the water in the 
narrow Strait of Messina .... In consequence of the strong 
currents sometimes .... not only many deep-sea fishes, but also 
all stages of the development of the Mura?noids are met with in 
the surface-water.” To this circumstance mainly, he owes the 
abundant material which enabled him to make his interesting 
investigations. He found that these currents occasionally carried 
to the surface, sometimes in large numbers, a form of Leptocephalus 
known as L. hrerirosfris, and it was in working out the life-history of 
this curious little animal, that he discovered it to be the larval 
form of the Common Eel. Dr. Grassi then proceeds to describe 
the progressive development of this singular little organism into 
the “elver,” which returns in the spring to stock the freshwater 
streams from whence its parents passed into the sea. These changes 
are extremely interesting, and some of them very extraordinary, 
but too technical to repeat here. 
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