6 9 



observer in Bulletin No. 3 of the Madras Government 

 Museum (1895), mentions that he ''obtained a few 

 specimens in the Gulf of Manaar and a large number 

 from the meshes of fishermen's nets at Gopalpur, where 

 they are known as sea-leeches." * At that date their iden- 

 tity with the eel-family was unknown and Dr. Thurston 

 quoted Gunther's strange theory that they represented 

 the larvae of various marine fishes living a pelagic life 

 in an arrested and abnormal stage of development ! 



The identity of these larval fishes once established, 

 the completion of our knowledge of the life-history of the 

 eel became a question of the greatest interest to marine 

 zoologists and to-day many of the blanks have been 

 filled up. The range of Leptocephalid larvae was ex- 

 tended into the Atlantic by the capture by Schmidt and 

 also by Holt in 1904 of single specimens in the Atlantic. 

 The following year Schmidt obtained numerous indi- 

 viduals by means of the Petersen net, and was thus 

 enabled to determine some of the oceanographic condi- 

 tions under which they occur. The chief facts ascertained 

 during these memorable investigations are that the 

 leptocephalids of North European eels are not hatched 

 in shallow seas and that they are most numerous along 

 the course of the narrow band lying between the 500- 

 and the 600-fathom line of the Eastern Atlantic. They 

 were taken at various depths down to 1,000 metres, a 

 depth where the temperature is above 42 Fahr. and 

 salinity above 35 per 1,000. The greatest hauls were 

 made in the neighbourhood of a depth of about 70 

 fathoms. Other facts lead to the belief that the breed- 

 ing of the eel occurs at great depths. Large specimens 

 of the adult form of the eel have been obtained by Grassi 

 and Calandruccio from the whirlpools in the Straits of 

 Messina which occasionally bring to the surface animals 

 known to live at abyssal depths ; these eels, while having 

 the dark livery of the breeding season, were more deeply 

 pigmented and were marked by an extraordinary increase 

 in the size of the eyes. Vaillant also records the 

 extraction of an eel, 90 centimetres long, from the 

 stomach of a Cachalot whale captured off the Azores. 



* The latter probably were not true Leptocephali ; it is more likely they were 

 elvers. J. H. 



