CHAPTER XII 



THE BULL HEAD AND THE STICKLEBACKS 



The Scorpcnenoids. 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 

 {Scorpcenidci), 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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