54 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



off Skye), splashing on the surface so as to give the appear- 

 ance of fine rain ; and this present occurrence at once reminded 

 me of the former occasion, but here the Copepod was Calanus 

 finmarchicus of large size and in extraordinary abundance. 

 They could be clearly seen with the eye on leaning over the side 

 of the boat, a small glass collecting jar dipped at random into 

 the water brought out twenty to thirty specimens at each dip, 

 and a coarse grit-gauze tow-net of about 30 cm. in diameter 

 caught about 20 cubic centimetres of the Copepoda in five 

 minutes. The mackerel were obviously darting about, 

 occasionally leaping to the surface (which gave the gulls their 

 opportunity) where the whirls, caused by the Copepoda, were 

 thickest, and an examination of the stomach-contents of the 

 fish on the yacht afterwards showed us that the amount in one 

 mackerel was about the same quantity as that caught by the 

 tow-net in five minutes. Professor Newstead and I have made 

 a count of 8 c.c. of the tow-net gathering, and estimate that it 

 contains about 2,400 specimens of Calanus. This would give 

 about 6,000 Copepods in the stomach of an average mackerel, 

 or in a five minutes' haul of the tow-net, on this occasion. 



" It may be added that these mackerel were evidently not 

 being nourished in accordance with the views of Putter, and 

 were clearly able to fill their stomachs from the plankton 

 around them. — W. A. Herdman. S.Y. ' Runa,' Tobermory, 

 Mull, July 12th." 



This had the happy result of causing several naturalists 

 to write to me privately stating that they had on occasions in the 

 past had a similar, but perhaps less striking experience ; and 

 the following letter to " Nature," from Mr. G. E. Bullen, 

 formerly of the Plymouth Marine Laboratory, appeared in the 

 issue of July 24th (p. 531) :— 



"Referring to Professor Herdman' s interesting observations 

 upon the above (' Nature,' July 17th), I may perhaps mention 

 that the mackerel-drifters, when fishing upon the usual grounds 



