THE GURNARDS, BULLHEADS, AND WEE VERS 145 



The fishes which occupy the present chapter fall under 

 three families. They are : — 



It will now be necessary to consider these somewhat in 

 detail. 



Cottidae 



The Bullheads and Gurnards 



Something has already been said of the differences between 

 these two groups. The habit of grunting — hence the French 

 "■' gourneau,'' and the English vernacular name " piper " of one 

 species — is commonly associated with the gurnards only ; and 

 Cunningham explains it as the sound produced by the expul- 

 sion of air from one chamber of the closed and partitioned 

 air-bladder to the other. This is probably correct, the only 

 objection to it being that some bullheads (hence the German 

 name for the Baltic sea-scorpion, " Knurrhahn ") also utter 

 these sounds, and the bullheads have no air-bladder. It is, 

 however, true that the noise made by the bullheads is much 

 weaker than that of the gurnards, and it may in their case be 

 merely the gasping expulsion of air at the gill-covers. The 

 grunting sound made by gurnards is, on the other hand, said 

 to be produced when these fish are still under water, though 



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