86 Proceedings of the Royal Irish Academy. 



have described certain migrations to nie, but no account of these migrations 

 seems to exist anywhere. It would be of great interest to follow this line up. 

 Moreover, there seems to be some difficulty even in getting figures for the 

 quantity of fish captured. The following figures have been kindly given by 

 Mr. E. W. L. Holt of the Irish Fisheries, and show tlie estimated captures for 

 seven years, 1905-1911 : — 



1905, . . 427 tons. 1909, . ' . 300 tons. 



1906, . '.384 „ 1910, . . 377 „ 



1907, . . 386 „ 1911, . . 240 „ 



1908, . . 233 „ 



We were usually given to understand in Belfast that the Pollan fed ou 

 Mysis — nothing else seemed to be mentioned. Tate Began records the staple 

 food to be Mysis relicta (which he incorrectly terms an Entomostracan), but 

 mentions that examination of their stomachs shows that they appreciate 

 insect larvae, shrimps ?, small bivalves, and the fry of other fishes. We have 

 examined large numbers of stomachs. In the summer months of 1910 we 

 never found Mysis relicta at all in the fish captured at Antrim. The alimentary 

 canals were literally black with the late pupal stages of Chironomus. Now 

 Chironomus larva occur in prodigious numbers in the mud at the bottom 

 of the lake. Other Pollan caught in summer, and particularly at Antrim, had 

 been feeding on Crustacea, both bottom and pelagic forms being included. 



From 45 Pollan, 851 Mysis relicta were taken on another occasion. The 

 easiest way to obtain Mysis relicta, except by plankton-netting at night, is to 

 catch the Pollan and examine the alimentary canals. From 43 Pollan the 

 following were taken : — 



204 Asellus, 

 99 Molluscs (Bivalves and Gastropoda), 

 5 Insect larvae, 

 and numerous smaller Crustacea, in addition to Mysis relicta. 



Huge numbers of Daphnids have been taken from the same Pollan. The 

 species include Bnphnia hycdina and Bythotrephcs longiinanus. The most 

 extraordinary thing, however, was that on most occasions when Daphnids 

 were found in the alimentary canals, practically nothing else was present. 

 The Crustacea were present in thousands. Moreover, we have never found 

 Bythotrephcs in our catches at all. 



There is still a very great deal to learn about the feeding methods of 

 aquatic animals, both vertebrate and invertebrate. At present, however, 

 since a detailed investigation is being conducted (Moore and others, 1912), 

 any discussion of this subject is inadvisable. 



