4 . Fishery Board for Scotland. 



either by way of tlie English Channel or round the Xorth of vScot- 

 land. 



The records from Scottish waters are of value, therefore, not only 

 in extending our knowledge of the northerly limits of distribution 

 of the Leptocephali, but also in defining more precisely the time 

 •and intensity of the migration of the young " glass eels " round the 

 North of Scotland. 



The Larvm of the Common Fresli^^cater Eel. 



Of the Leptocephalis larvae of the Common Eel only 13 specimens 

 have been obtained in the course of our work ; and that the 

 Scottish records of Leptocephali are not more numerous is simply 

 to be accounted for by the infrequency of our visits to the deep 

 Atlantic waters of the west coast. Dr. Schmidt has shown that 

 the Leptocephali are found outside the 1000-metre line, but in 

 decreasing abundance towards the north. One of onr thirteen 

 specimens was got within this 1000-metre area at 58° 43' N. 9° 45' 

 W. on August 23rd, 1910. It was at stage three of the retrogressive 

 metamorphosis, and is thus only an additional record to the normal 

 distribution found by Schmidt. Most of our Scottish stations have 

 been to the north of this 1000-metre line, and the other twelve 

 specimens captured are of interest as being apparently sporadic 

 examples which liaA^e been driven early from the main stock of 

 Leptocephali by the strong current iiinning towards the north-east. 



Perhaps the most interesting of these records is an example which 

 had been earned away to the N.E. over the Wyville-Thomson ridge, 

 into the Faeroe- Shetland Channel, and which even in the month of 

 August had reached a higher latitude than the north point of Shet- 

 land; it was found in 61° 17' N. 1° 22' W. This specimen, 

 75 mm. in length, was not very far advanced in its metamorjihosis, 

 and had onlv reached stage two on the 11th of August. A specimen 

 which was caught on July 6, 1904, at 59° 61' N. 6° 00' W., and 

 which still retained its lai'val teeth, not having begun the retrogi'ade 

 metamoi-phosis, shows us how in some years the ]ire vailing drift 

 may drive the larvae inwards very early. The records of the other 

 two stations also help to show this, and indicate that even in August 

 many of the lai-vae are far advanced in their retrograde meta- 

 moqihosis. At 59° 15' N. 7° 10' W. one had proceeded so far as 

 stage four, one had reached stage three, another between stages two 

 and three, whilst the other six specimens taken on the same station 

 at the same time were at stage two. 



In spite of the fact that our observations are comparatively few, 

 and that our work in the deep waters has been practically confined to 

 the months of July and August, these records of the Leptocephali 

 help us considerably towards an understanding of the route taken 

 round the North of Scotland by the immigrating lai-vae. Had our 

 work in the Atlantic, and that around the North of Scotlana, 

 extended through the months of September, October, and Novem- 

 ber, then we should have doubtless been able to trace in a more 

 thorough way the migration of the Leptocephali, and of the glass-eel 

 into which they presently turn. Our more continuous work in the 

 North Sea itself throws a good deal of light upon the distribution of 

 these glass-eels. 



