292 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1924 



ber, but decrease in size from east to west. This placed it beyond 

 doubt that the stock of eels in Europe must have its origin in an 

 area situated far to the west in the Atlantic Ocean. 



The question now was, what further conclusions could be drawn 

 from the wealth of material obtained from the Margrethe's 73 

 stations, comprising as it did, apart from larvte of the fresh-water 

 eel, close on 10,000 larvae of other eel fishes. 



In October and November, and the early part of December, 1913, 

 the Margrethe was working in the western part of the Atlantic, be- 

 tween Newfoundland and the West Indies, in the course of which 

 cruise the northern and southern limits of distribution of the larvae 

 of the European eel were determined. They were found to occur 

 from about 40° N. latitude (a bare 200 miles south of the New- 

 foundland Banks), to about 24° N. latitude. To the westward speci- 

 mens were found as far as our investigations reached, viz, to Ber- 

 muda and the sea to the south of there, i.e., to about 65° W. longi- 

 tude, and even here they were present in great numbers. This was 

 an astonishing fact, for one would hardly have expected to find the 

 larvje of our European eel as a numerous population in Atlantic 

 waters so far west as 65° — New York lies about 74° ! Larvae of 

 the American eel were also taken in our nets, but in remarkabh' 

 small numbers, amounting to only some few (3-4) per cent of the 

 total number of Anguilla larvae.^ Here, again, a new problem 

 arose ; for how could it be that Bermuda M^as, as it were, surrounded 

 by a belt of larvae of the European eel, when all the specimens of 

 fresh-Avater eels I had previously examined from these islands had 

 proved to belong to the American Anguilla rostrataf It was not 

 until several years after that we were to learn the explanation of the 

 mystery; the time was not yet ripe for its solution. 



"VVe now come to the size of the eel larva3 taken on the cruise of the 

 Margrethe. The smallest eel larva hitherto known was, it will be 

 remembered, one measuring 34 mm. in length, but this was only 

 a single isolated find, and did not count for much. On the other 

 hand, it was to be expected that the great mass of material from 

 the Margrethe^ systematically collected as it was, would furnish 

 valuable data as to the size of eel larvae in autumn. We were, of 

 course, still without any answer to the important question as to 

 whether larvae were produced uninterruptedly throughout the year, 

 or if a particular season of the year could be defined as the breed- 

 ing season of the eel. Not until these points were settled should 

 we have anything to go upon in judging the age of the older larvae 

 from the central and eastern Atlantic. 



> The lai-va of the American eel was described In 1002 by Eisjenmann and Kennedy 

 I'rom two specimens, 47 and 49 mm. in length, taken by the U. S. S. Albatross in 1883 

 at .about 38°-39° N. lat., 72°-73° W. long:. (Bull. U. S. Fish Commission, XXI, 1902). 

 I do not know of other records from the literature of the larva; of the American eel. 



