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ON THE EDUCABILITY OF THREE EOCKLINGS AND A 

 SEA-BULLHEAD. 



By H. N. Milligan. 



Precise notes are rarely made upon the behaviour of common 

 sea-shore fishes during the first few days of their residence in 

 aquaria, or upon the length of time which may elapse before 

 they begin to look for and to accept food from their owner. 

 Such detailed records (not general statements, which are nearly 

 useless) will be of great value when a sufficient volume of them 

 has been obtained. Attention has already been drawn to this 

 subject in the ' Zoologist ' (" Tameness in Several Blennies " 

 and " Tameness in a Sea-Bullhead," 1915, pp. 358-9; " Educa- 

 bility of Galathea strigosa, 1916, pp. 297-8), and I should 

 now like to describe additional examples of educability in 

 three individuals of the Five-bearded Eockling (Motella mustela) 

 and in a Sea-Bullhead (Cottus bubalis). The statements con- 

 tained in this paper are simply those of fact, and no attempt is 

 made to express opinions. It may also be remarked that all the 

 simple modifications of behaviour observed were such as sprung 

 naturally out of the fishes' new environment, and the animals 

 were not " taught " nor set "tasks " to perform. 



(1) On October 9th, 1915, a Rockling of three and a half 

 inches in length, obtained from Weymouth, was placed in an 

 aquarium. The tank contained about twenty- seven gallons of 

 water and a mass of rockwork which provided convenient hiding 

 places for the fish. The Eockling, as is usual with individuals 

 of this species, remained almost motionless and almost completely 

 hidden (during the daytime at least) in recesses of the rocks 

 during the first few days of its captivity. On the morning of 

 October 14th, however, when its head was observed to be pro- 

 jecting slightly from the rocks, the fish was induced to take, 

 apparently without fear, a piece of raw beef from the wooden 

 feeding-forceps. On the morning of the 15th (that is, during the 

 sixth day of captivity), when the fish was lying fully exposed on 

 the rocks, the food-tainted forceps were gently laid against its 

 snout. The fish at once began to examine the forceps, swimming 



