CHAPTER XII 

 THE BULL-HEAD AND THE STICKLEBACKS 



The Scorpaenoids. The Bull-head described distribution 

 size habits breeding care of eggs and young uses of 

 spines rapid changes of colour tenacity of life as food and 

 bait. The Gastrosteoids. The Stickleback family : the Three- 

 spined Stickleback size distribution specific characters 

 variation in lateral plates short-spined form southern fresh- 

 water colonies specifically distinct four-spined examples 

 experimental transference from fresh to salt water size of 

 shoals uses pugnacity and voracity nest-building breeding 

 habits combats care of eggs and young the Ten-spined 

 Stickleback differences from the preceding distribution 

 geographical races the British form short-spined variety 

 without pelvic fins coloration habits 



THE Scorpaenoid group differs from the 

 Percoids in a single feature, namely, the 

 prolongation of the second suborbital bone across 

 the cheek to or towards the praeopercle. Slight as 

 this difference may seem, it is, nevertheless, very 

 important, as with one exception this feature persists 

 in all the numerous members of the suborder, in- 

 cluding such diverse types as the Rock-perches 

 (Scffrp&nida), Gurnards (Triglidce}^ Flying Gurnards 

 (Dactylopteridce}) Lump-suckers (Cyclopteridce), and 

 Bull-heads (Cottidce} ; the single exception is the 

 aberrant Comephorus from the depths of Lake 



Baikal, which has a very feebly ossified skeleton. 



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