of the Fishery Board for Scotland. 



281 



VIII. — ICHTHYO LOGICAL NOTES. 



By Dr. T. Wemyss Fulton, F.R.S.E., Superintendent of 

 Scientific Investigations. 



[Plate XVIII /| 



CONTENTS. 



The Young of the Conger, 



A Larval Fierasfer, 



The Sting Ray, - - - 



The Pilchard, - 



The Fecundity of the Sprat, 



An Albino Plaice, 



The Thickback (Solea variegata), 



Reversed action of the Gill-cover in Plaice, 



PAGE 

 281 

 283 

 283 

 284 

 285 

 286 

 286 

 287 



The Young of the Conger (Leptocephalus). 



Two specimens of the young of the conger eel were caught in the 

 Moray Frth by means of the small-meshed net around the otter trawl, 

 which has been so productive of rare forms, and as such specimens 

 are very rarely obtained in British seas, and they differ from one 

 another in age and characters, I have thought it desirable to give a 

 descriptiou and figures of them here. 



The first specimen (Fig. 1) was obtained on 27th December on Smith 

 Bank, a well-known fishing ground off the coast of Caithness, in 28 fathoms 

 of water. It was not recognised at the time among the other fishes 

 caught and the lot were preserved in formaldehyde and taken to the 

 marine laboratory at the Bay of Nigg. It was only later, when the 

 material was being worked up, that the specimen was discovered. With 

 the exception of a slight abrasion on the posterior half it was in good 

 condition ; the imperfection was probably due to the fish having been 

 caught by doubling as it passed through the mesh of the net. On 

 examination some weeks after it was caught it was found to be trans- 

 lucent, with a whitish opacity, the perfect transparency of the living 

 form having been affected by the preservative. It was quite soft and 

 flexible, resembling a tapeworm in these respects, as well as in its 

 extremely flattened form. In extreme length it measured 145mm., 

 (5| inches), and it is therefore among the largest of the specimens 

 recorded. Its weight, after the superfluous water had been removed, was 

 only 0-61 grammes, and its volume was 1*1 cubic centimetres as nearly 

 as could be determined. Its bulk in proportion to its length, as will be 

 seen below, was thus very much under that of the other older but 

 shorter specimen. 



The extreme dorso- ventral height of the body was 13'5mm., and it 

 was broadest from about 70 to 95mm. from the head ; the height just 

 behind the head was 7mm., or about half of the other. The thickness 

 of the body was difficult to determine ; it was much thicker behind the 

 head, where it measured about 2mm., and from this point to the 

 posterior extremity it gradually diminished, the greater part of it being 

 rather under than over 1mm. in thickness. The length of the head 

 from the tip of the snout to the gill-cleft measured 10mm., and its 

 height at the eyes was 5mm., the breadth being 3mm. just behind the 



