374 GB; GRASSI. 
near the tip of the tail. The larva then becomes a hemi-larva, 
the two apertures 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 larva, as well as the hemi-larva, 
shows a length of body much greater than that exhibited by 
the young Murzenoid of adult form into which they are trans- 
formed. By keeping specimens in an aquarium I was able to 
establish a diminution of more than 4 cm. during the meta- 
morphosis. With regard to the greatest length which the larva 
can attain in a given species, and the amount of diminution 
which accompanies metamorphosis, there are great individual 
variations. 
The history of the common eel, to which I am now about 
to refer, is very similar to that given above for the other 
Murenoids. The common eel (Anguilla vulgaris) under- 
goes a metamorphosis, and before it assumes the definitive 
adult form it presents itself as a Leptocephalus, which is known 
as Leptocephalus brevirostris. This Leptocephalus was 
discovered in the Straits of Messina many years ago. A speci- 
men was also captured by the ‘‘ Challenger,” and another 
specimen was taken by the Zoological Station of Naples in the 
Straits of Messina. This form is occasionally carried to the 
surface by currents. By exception, in the month of March, in 
the year 1895, we captured several thousands of them in one 
day ; but the best way to secure this Leptocephalus (and a very 
easy one) is to open the intestine of the Orthagoriscus 
mola, a fish which is common in the Straits of Messina, and 
in it one is certain to find a very large number of specimens. 
It must be observed that Orthagoriscus mola is a deep-sea 
fish. The specimens of Leptocephalus brevirostris found 
in the intestine of Orthagoriscus are more or less altered by 
digestion. Those specimens of Leptocephalus brevirostris 
which are taken near the surface in the open sea are in a better 
state of preservation, but, unfortunately, these also frequently 
have the epidermis injured so that they cannot maintain their 
life in an aquarium for more than a few days; they live long 
