28l 



coast of India, where on the disappearance for several succes- 

 sive seasons of the oil sardine, sharks, saw fishes and skates 

 were absent, while all these forms returned simultaneously. 

 We see also on our coasts the strong follows the weak, and 

 preys upon him if a sufficiently dainty morsel. 



The mackerel, it has been observed, swim higher or lower 

 in the water in accordance with atmospheric vicissitudes, 

 most probably due to the influence of such upon the food 

 they subsist upon. Thanks to Mr. Dunn, of Mevagissey, 

 I have had the opportunity of investigating the food con- 

 sumed by the mackerel at various seasons of the year, 

 when I was not able to be on the coast : in the summer 

 and autumn they follow the herring and take heavy toll, 

 especially during the later months of the year, upon the 

 britt, which are the fry of those fishes and of the sprat. 

 About the middle of May along the south coast they are 

 especially partial to the mackerel midge, which is the young 

 of rockling (Motelld). They also prey upon small crustacean 

 forms. In March, 1882, the contents of the stomach of some 

 of these fishes, sent me from Mevagissey and which had 

 been captured eight miles from land in over forty fathoms of 

 water, consisted of small crustaceans Thysanopoda Couchii, 

 which form was originally procured by Couch in a similar 

 mamier. In May, 1880, I opened a number from the south- 

 west coast, all were gorged with ova. In May, 1883, Mr. 

 Dunn found Mevagissey Bay swarming with entomostraca, 

 and similar animals were present in the stomachs of the 

 mackerel and pilchards. These copepods consisted of 

 Centropages typicus, Kroyer ; Temora longicaudata, Lub- 

 bock ; Calanus Finmarchicus, Gunner (A. Norman). 

 Mackerel consume other fish, following the herring and 

 their young, the fry of the rockling, various forms of 

 Crustacea, also of ova, and In fact prey upon a large amount 



