SEA-FISHERIES LABORATORY. 85 



the end of the previous year, or very early in the spawning 

 season, and keep them alive in a suitable pond, allowing 

 them to shed the eggs by their own efforts. 



That the water is satisfactory for the purpose is proved by 

 the result of the past year's hatching work. After passing 

 through the filter it was perfectly pure and transparent, 

 the specific gravity varying from 1"0025 to 1'0026, and the 

 temperature from 4° C. to 4*8° C. 



The mortality of the larvae kept after hatching is very 

 serious. Further experiments will be tried, as it may be 

 that we have merely not yet hit upon the proper food. 

 It may, however, be found best to set the young fish free 

 before they reach the critical stage in their development. 



Observations on the Occurrence and Habits of 

 Leptocephalus. 



(Andrew Scott.) 



In recent years much light has been thrown upon this 

 peculiar group of fishes (the Leptocephalidae), which were 

 at one time considered to be fully developed animals and 

 classed by naturalists as such, under the generic name of 

 Leptocephalus. Thanks to the observations made at 

 Koscoff, in France, in 1886, the form then known only as 

 Leptocephalus morrisii, was actually observed to change 

 into the Conger eel (Conger vulgaris) , and later, in 1891-95, 

 two Italian investigators, Grassi and Calandruccio, carried 

 on careful experiments on the Leptocephalus brevirostris 

 taken in the Straits of Messina. They found that this 

 so-called species went through a transformation, changing 

 into the common Eel, Anguilla vulgaris.* So that there 

 can no longer be any doubt now that the Leptocephall of 

 the older naturalists are only the larval stages of Eels. 



* Proceedings Royal Society, London, vol. LX., No. 363. Dec, 1896. 



