BEEEDING PLACES OF THE EEL SCHMIDT 305 



take a more direct northeasterly course from the breeding grounds. 

 The probability is that differences will be found to occur in this 

 respect as between one year and another and also as between differ- 

 ent parts of the breeding grounds. 



Anyhow, the result of the movement is that no full-grown larvse 

 of the European eel are met with in the western Atlantic. As al- 

 ready mentioned, it was altogether exceptional to find specimens 

 over 50 mm. in length west of 50° W., and we have never taken a 

 single one over 60 mm. in this portion of the ocean (cf. fig. 7). 



During the initial period of our investigations in the eastern At- 

 lantic and the Mediterranean we had no occasion to concern ourselves 

 with the American eel {Anguilla rostrata) and its larvae. Later on, 

 however, circumstances changed, after it was found that our re- 

 searches in connection with the European species would have to be 

 extended farther west. The collections here made by the trading 

 vessels, and by the Margrethe in 1913, brought us already certain 

 specimens which, though outwardly indistinguishable from Lepto- 

 cephalus brevirost7'is, proved, on being tested for number of muscle 

 segments (myomeres), to belong to the American eel. These larvae 

 were taken in the same area as those of the European species, even, 

 indeed, at one or two of the Margrethe's stations, in the same haul. 

 It was with mingled feelings that we noted this fact, since it involved 

 a further complication of the eel question, which at this point seemed 

 more intricate than ever. Technically, also, it increased the diffi- 

 culty of our investigations, since the only means whereby the larvse 

 of the two species can be distinguished one from the other is by 

 counting, under the microscope, the 104-120 myomeres in each in- 

 dividual specimen — a very lengthy and laborious business, especially 

 on board a small vessel at sea. 



After the cruise of the Dana, in 1920, I look upon the matter in 

 quite a different way. True, the technical difficulties have not dimin- 

 ished — I have in mind the counting of myomeres in the thousands of 

 specimens obtained on the cruise — but the comparison of the life his- 

 tory of the two species which our investigations have enabled us to 

 make is, to my thinking, one of the most interesting chapters in the 

 history of the eel. Indeed, it is hardly too much to say that the life 

 history of the European eel can only be properly understood at all by 

 comparison with that of the American. This will be seen from what 

 now follows. 



At the Dana station 827, southeast of Bermuda (30° 47' N., 62° 

 27' W.), we made a haul on June 13, 1920, at about 25 meters depth, 

 bringing up 150 Anguilla larvae. Tliese were measured, as usual, as 

 soon as possible after preservation, giving the result shown in Figure 

 •12, A. Believing that we had here solely to deal with Le-pto- 

 cephalus brevirostris, we naturally regarded the haul as practically 



