— 178 — 



of fish young were also found as in June, but fewer both in quantity and quality. As 

 mentioned we took in all 8 specimens of Leptocephalus brevirostris, 4 of which were 

 in the 2nd stage, 3 in the 3rd, and 1 in the 4th (cf. Figs. 3—9, Plate VIII). All the 8 spe- 

 cimens were taken with the young-fish trawl, .200, 250 and 300 meters wire respectively 

 being out, whereas a haul with 1500 meters wire out gave nothing. The eel larvae 

 thus seemed to occur not only at the same places but also in the same depths as in 

 June, but whether they now also occurred right up to the surface as well as in depths of 

 ca. 75 — 125 meters (young-fish trawl with 200 — 300 meters wire) I am unable to say, as 

 the heavy swell did not permit us to use the apparatus with less than 200 meters of 

 wire out. 



With a single exception all our September specimens were alive when brought up 

 in the trawl and I therefore placed them in a large glass full of sea water in order to 

 more closely investigate their appearance and movements. They were all glass-clear 

 and just as transparent as those we had taken earlier, in June. The iris was silvery but 

 otherwise very little was seen of the specimens in the water. In movements they quite 

 resembled specimens of the 2nd and 3nd Stage (cf. PI. VIII, Figs. 3—8) of June and thus 

 moved forward, not very rapidly, with eel-like sinuations of the body. Often they seemed 

 to remain quite still in the water. In order to preserve them I brought them into a shallow 

 glass basin with weak formaline in which they were very quickly killed without attempting 

 to move further. 



The single specimen present of the 4th Stage was quite different. As will be remem- 

 bered and as can be seen from the figure 9 PL VIII, it was much narrower (and at the 

 same time much thicker) than the others, yet nevertheless perfectly glass-clear and trans- 

 parent. When placed in the glass with sea water this specimen moved extremely quickly 

 about with arrowlike swiftness and thus gave quite a diff'erent impression from the other, 

 younger specimens. Also, when placed in formaline it acted very differently, repeatedly 

 springing out from the shallow basin with powerful movements on to the table and 

 thence on to the floor in the laboratory on the ship, so that I was finally obliged to put 

 a lid over the basin to get it killed, which took a considerably longer period than for the 

 earlier, flatter specimens. , 



I have mentioned this observation somewhat closely, as is shows that, towards the 

 end of the stay over the deep water, that is, at the stage when the height of the body 

 becomes greatly reduced, the eel larvae are considerably stronger and more swift 

 in movements than in the earlier stages, a condition perhaps not without its 

 importance for the comprehension of their later migration towards the coasts. 



In addition to our own observations, some discoveries are also to hand from the 

 Irish side which support in great measure and supplement our Danish. These have been 

 kindly placed at my disposal by the director of the Irish investigations, Mr. E. W. L. Holt 

 of Dublin. They were made by the Irish investigation-steamer "Helga" in November 1904 



1 Two specimens were also taken of one of the June Leptocephalus-species, viz. a characteristic, pig- 

 mentless form with ''telescope"-eyes. One of the.se specimens was taken deep in the water (1200 m. wire) and 

 was further forward in development than the other which was taken near the surface (200 meters wire); this 

 probably is in connection with the fact that this Leptocephalus belongs to a deepwater eel, namely, Syna- 

 phobranchtis pinnatus and thus seeks deeper water during metamorphosis, whilst in the Leptocephalus stage 

 it keeps nearer to the surface like Lept. brevirosiris. 



