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well to the east of that of the American Eel, and that the larvae 

 of the two species would not be found in the same waters. 

 Schmidt was therefore greatly puzzled when he began, in the 

 Western Atlantic, to take larvse of both species in the same hauls, 

 and it is indeed surprising that although all the eels of Bermuda 

 belong to the American species hosts of larvse of the European 

 Eel occur in the waters round that island. Seeing that the 

 larvae occur together in the Western Atlantic, why has Europe 



Fig. 2. — European Eel {Angjiilla vulgaris) and American 

 Eel {Angtiilla rostrata). 



Breeding areas and distribution of larvx shown by curves (dotted for the American, 

 continuous for the European species). The heavily drawn innermost curves embrace the 

 breeding areas of the two species. The curves also show limits of occurrence — i.e. speci- 

 mens less than 25 mm. in length have been found only inside the 25 mm. curve, etc, (from 

 Phil. Trans. R. Society). 



one species of Eel and America another ? The answer to this 

 question was found to be as follows : In the American Eel the 

 pelagic larval stage ends in about a year, consequently the larvse 

 have not time to make the journey to Europe, and any that 

 move eastwards will change into elvers in the middle of the 

 Atlantic. The European Eel takes three times as long over its 

 larval development, so that its larvse are far away from 

 America when the time comes for them to change into elvers, 

 and any that move to the west or north-west will reach the 

 American coast as small larvse. This different duration of the 



