— 176 — 



If we compare these measurements with those given earlier, we see that the eel young 

 have already reached their minimum size in June (average about 66 mm.) as also that 

 this can vary according to the different localities. We see further that the eel young 

 increase next to nothing in length during the summer. From some measurements pub- 

 lished by A. C. JoHANSEN (1. c, p. 7) of young eels taken in a stream at Frederikshavn 

 (east coast of Jutland) on Oct. l8th, 1904, we also find that most of the specimens are 

 now about 8 and 7 centimeters in length (average length is given as a little below 8 cm.). 

 This means that the young eels have only just reached the length they had 

 earlier as Leptocephali 16 months before (inJune of the previous year). Further 

 there can be no doubt that the growth during the period just after the end of the meta- 

 morphosis is very different in different places. That there may even be a difference by 

 no means inconsiderable at places quite near to one another is shown by the accom- 

 panying measurements No. VIl and VIII. 



(c) The mode of life of the eel larvae (L. brevirostris). The June specimens 

 may be considered first of all. There can no longer be any doubt after our investiga- 

 tions in 1905 that Leptocephalus brevirostris is a true pelagic form which has 

 nothing to do with the bottom'. This appears with the greatest clearness from all 

 our hauls with the young-fish trawl. As specially apt in this regard I may give the result 

 of our observations at a single station. 



Station 82, 14th June 1905 

 Lat. 5l°oo' N. ; Long. ll°43' W. ; Depth about 1200 meters: 



(1) Young-fish trawl, 200 meters wire out, l hour gave 



(2) — 300 — — — 2 — — 



(3) — 300 — — — 2 — — 



(4) — 600 — — . — 2 — — 



(5) - 800 - - - 2 - — 



(6) — 1200 — — — 2 — — 



5 Lept. brevirostris 

 38 - - 



22 — — 



18 — 



8 — — 



These hauls show quite clearly that the eel larvae are more numerous in the 

 upper water layers than in the lower. No hauls were made nearer the surface^' 

 at this station, but on another occasion where such were made, it was found that Lept 

 brevirostris may also occur right at the surface. They seem however to be most 

 numerous at some distance below the surface. Thus most specimens were taken with 

 from 2—300 meters wire out, which corresponds to a depth of about .100 meters, 

 but just as with so many other fishes and animals the eel larvae seem to be found 

 nearer the surface at night than in the day. 



I The mode of life of the preleptocephalic stages is a different question but these two things must be 

 kept quite apart from one another, which has not always been done hitherto. 



= Relatively few hauls were taken on the surface, as the net is more easily ruptured in the heavy swell 

 often prevailing over great depths when towed near the surface than when deeper down (the greater length 

 of wire has more spring in the swell). 



