292 THE ZOOLOGIST. 



forceps through the water as though seeking for further food. 

 By January 1st (twenty-fourth day) it had become accustomed to 

 taking food from my fingers. On January 6th (twenty-ninth 

 day) it was noted that the Kockling was awaiting food, along 

 with the second Eockling, at the corner of the tank, and it 

 continued to do this. Both Bocklings died in February. 



In order that the importance of the foregoing facts may 

 be appreciated it must be observed that the Five-bearded 

 Eockling is an exceedingly timid nocturnal fish which, dreads 

 light and light-coloured surfaces. J. Stuart Thomson (" The 

 Dorsal Vibratile Fin of the Eockling (Motella)," ' Quart. Journ. 

 Micro. Sci.,' No. 229, vol. 58, N.S., September, 1912, p. 250) 

 mentions that in his observations upon Eocklings it was neces- 

 sary to keep even the light of a candle in a more or less shaded 

 place. 



On December 8th, 1915, a Sea-Bullhead (Cottus bubalis) of 

 three and a half inches in length, from Weymouth, was placed 

 in an aquarium which already contained several large individuals 

 of the Goby (Gobius paganellus). It should here be remarked 

 that the Sea-Bullhead finds food mainly by the sense of sight, 

 whereas the Eockling finds food by touch, taste, and smell. 



The Bullhead was at first very timid, and invariably retreated 

 by swimming heavily and jerkily through the water when the 

 forceps were placed close to its body. The fish lay for the 

 greater part of the time partially embedded in the pebbles of 

 the bottom, or clinging with its spreading pectoral fins to the 

 vertical rockwork at the back of the aquarium. On the morning 

 of December 10th (that is, during the second day of captivity) a 

 piece of mussel, and afterwards a piece of raw beef, was offered 

 to the Bullhead in the forceps, but the fish appeared to take 

 no notice of the food, and swam away when the pieces of beef 

 and mussel were thrown on the bottom close to its head. The 

 Bullhead again refused beef and mussel on the 11th. On 

 the morning of the 17th (ninth day) it took three successive 

 pieces of beef which were thrown into the water, but it would not 

 approach a piece which was held towards it in the forceps. The 

 jerky movements of the Gobies, which are in the habit of darting 

 rapidly out of their holes to seize food and then darting back 

 again, probably added to the Bullhead's fear of the forceps. It 



