MARINE BIOLOGICAL STATION AT PORT ERIN. 21 



during the latter part of March. The behaviour of these 

 unfertilized eggs is puzzling, and requires further 

 observation. It is known that they will float at the surface 

 of the water for a week, and many were found so floating 

 in our pond every time the skimming net was used. But, 

 even when transferred from the net to a glass dish by 

 means of a jar dipped into the water included in the net, 

 they invariably sank to the bottom of the dish when 

 placed therein, and the same change occurred, though 

 more gradually, when they were subjected to the 

 circulation and agitation of the hatching boxes. The 

 extent to which the eggs of marine fishes escape 

 fertilisation in nature is a question that has been 

 frequently discussed, and it was with no little interest 

 that we found that a tow-netting taken in the open sea by 

 the Assistant Curator in April last contained a large 

 number of undoubtedly unfertilised eggs, probably those 

 of the common dab. 



Frequent observation showed that the buoyancy of the 

 fertilised eggs increases as the development of the larva 

 proceeds, and at what might be called the middle period 

 of embryonic development there is a marked tendency on 

 the part of the eggs to congregate in masses at the surface 

 of the water in the hatching boxes. 



After the liberation of the last batch of young fry, 

 the spawning-pond was drained, and the fish therein 

 examined. With one exception, all the adult females 

 were found completely spent, but the most interesting 

 discovery was that of a large number of young fish which 

 had been hatched during the season of 1904. Nearly a 

 hundred of these were caught, and 32 taken at random 

 were found, on measurement, to range from 2f inches 

 to 5 J inches, the average length being 4*4 inches. 



The difficulty of obtaining an adequate supply of 



