530 Part III. — Tiventieth Annual Report 



centimetres in length. The only food observed in the stomachs of this 

 sample consisted of larval Crustaceans. 



The Herrings from the Firth of Forth measured from four to nearly 

 five inches (10 to 14^ cm.) in length ; the stomachs of all the specimens 

 contained food which for the most part consisted of pelagic Copepods 

 and larval Balani (cypris stage). Oiliojjleurce were moderately common 

 in at least eight of these stomachs. The Copepods most frequently 

 observed were Pseudocalamis elongatus, Temora longicornis, and 

 Cenfropages hamatus ; Podon leuckartii (G. 0. Sars), one of the Cladocera, 

 was also of frequent occurrence. A few other organisms were occasionally 

 noticed ; but those mentioned above formed the chief constituents of the 

 food of this sample of Herrings. 



In June, 1900, a shoal of young Herrings came into the Bay of Nigg ; 

 fifteen of them, collected on the 19th, and measuring from 5|- to 6|- 

 centimetres, were examined, and the food contained in their stomachs was 

 found to consist entirely of Copepods, some of which were pelagic, while 

 others were demersal forms. The species identified were Temora longi- 

 cornis, Idya furcata. and Dactylopus tishoides. 



A small lot of average-sized Herrings, collected off Aberdeen on 

 August 14th, had apparently, like those from the Bay of Nigg, been 

 living entirely (or largely) on Copepods — no other organisms being 

 observed in their stomachs — but the specimens were scarcely perfect 

 enough for identification. 



A sample of Herrings from Aberdeen Bay, collected on November 

 11th, 1900, and measuring from 13 to 14| centimetres in length, had 

 nothing in their stomachs that could be identified. Another lot, also 

 from Aberdeen Bay, and comprising thirty-one specimens, measuring 

 from \2\ to \fi\ centimetres, were collected on December 17th, 1900. 

 The stomachs of all these specimens contained a considerable amount of 

 food, which consisted very largely of Paratheniisto ohlivia and Sagitta ; 

 Calanus jfi7imarchicus occurred also sparingly in nearly all the stomachs; 

 but this species, except in a very few examples, formed but a small propor- 

 tion of the food. Temoralongicornis, Metridia hicens, Candacia j^edinata, 

 and fragments of a Schizopod ("Euphausida") were occasionally observed, 

 but, as already stated, the principal constituents of the food of these 

 Herrings were Paraihemisto and Sagitta. It will be observed that the 

 food of this sample of Herrings is in marked contrast to that 

 found in the stomachs of those previously described. I do not remember 

 having formerly observed Sagitta so plentiful in the stomachs of fishes as 

 a constituent of their food. Many observations have been made on the 

 food of fishes, but they were frequently made under conditions that did not 

 admit of exact microscopical examination, and the presence of Sagitta may 

 have thus at times been overlooked. It has also to be remembered that 

 the Sagitta, like other creatures not protected by a chitinous or calcareous 

 test, are readily acted upon by the gastric fluid and soon become 

 unrecognisable, so that unless the fish had been feeding on these organisms 

 shortly before or about the time it was captured they may become so 

 much decomposed as to be indistinguishable. 



In order to indicate more clearly the peculiar character of the food 

 found in the stomachs of these Herrings I subjoin a short extract from the 

 records made when the fish were examined : — 



[Table. 



