GEN. GASTEROSTEUS. RIVER BULL-HEAD. 161 



ferocious battle ensues : the two combatants swim 

 round and round about each other with the greatest 

 rapidity, biting and endeavouring to pierce each 

 other with tbeir spines, which on these occasions 

 are projected. I have witnessed a battle of this 

 sort which lasted several minutes .before either 

 would give way ; and when one does submit, ima- 

 gination can hardly conceive the vindictive fury of 

 the conqueror ; who, in the most persevering and un- 

 relenting way, chases his rival from one part of the 

 tub to another, until fairly exhausted with fatigue. 

 They also use their spines with such fatal effect, 

 that, incredible as it may appear, I have seen one, 

 during a battle, absolutely rip his opponent quite 

 open, so that he sank to the bottom and died. I 

 have occasionally known three or four parts of the 

 tub taken possession of by as many other little 

 tyrants, who guard their territories with the strictest 

 vigilance; and the slightest invasion invariably 

 brings on a battle. These are the habits of the 

 male fish alone : the females are quite pacific, ap- 

 pear fat, as if full of roe ; never assume the brilliant 

 colours of the male, by whom, as far as I have ob- 

 served they are unmolested." 



(Sp. 27.) G. semiarmatus. The Half-armed 

 Stickleback. This species has a strong general re- 

 semblance in size, colour, habits, &c. to the forego- 

 ing, and yet, according to the judgment of many 

 excellent Naturalists, is entitled to be considered as 

 an independent species. Its specific characters con- 

 sist in its lateral plates not extep-^ing beyond the 



L 



