THE GOBIES, SUCKERS, AND BLENNIES i6i 



convenience to these shallow-water dwellers in rough weather, 

 when the swirl of the surf would otherwise dash them ashore 

 or at any rate transport them far from their eggS. Other 

 fishes, not provided with these suctorial fins or discs, have to 

 burrow in the sand ; * and Cunningham gives a most interest- 

 ing account of an experiment by which he discovered the 

 manner in which the topknots {Zeugofterus), a group of flat- 

 fishes particularly given to a rocky dwelling, contrive to cling 

 to the vertical glass wall of an aquarium tank. By ingeniously 

 colouring the water with carmine particles, he was able to 

 ascertain the nature and direction of currents in the water 

 produced by the fish pumping water with its fins from between 

 its body and the glass and thereby setting up enough difl^erence 

 in pressure to keep it in position. In order to satisfy himself 

 beyond doubt that such was the case, he constructed an imita- 

 tion topknot of indiarubber with a siphon tube, and his 

 artificial flat-fish behaved exactly as was expected of it, falling 

 away from the glass the moment he checked the action of the 

 siphon. In view of what was said above of the convenience 

 of such methods of adhesion to shallow water fishes, the top- 

 knot's preference for a rocky ground, whereas most other 

 flat-fishes prefer the sand, is interesting. 



The most familiar foreign relatives of the gobies are the 

 grotesque little Mudskippers of the South Pacific. Their 

 strangely protruding, mobile eyes stare like those of the 

 chameleon, and they jump over the wet and treacherous sand 

 of North Australian estuaries more like frogs than fishes. 



Callionymidae 

 The Dragonets 



Closely related to the gobies are the two Dragonets 

 {Callionymida). As in so many of our wild birds, the male 



* See an interesting paper by Hunt and Jeffreys on " The Influence 

 of Wave Currents on the Fauna inhabiting Shallow Seas " {/ourn. Linn. 

 Soc, 1885, pp. 270-271). 



II 



