2 SEXUAL SELECTION". [Part IL 



are only temporarily developed during the breeding-sea- 

 son ; and Di-. Giintlier suspects that they are brought into 

 action as prehensile organs by the doubling inward and 

 downward of the two sides of the body. It is a remark- 

 able fact that the females and not the males of some spe- 

 cies, as of liaia clavata, have their backs studded with 

 large hook-formed spines.' 



Owing to the element which fishes inhabit, little is 

 known about their courtship, and not much about their 

 battles. The male stickleback ( Gasterosteus leiurus) has 

 been described as "mad Avith delight" when the female 

 comes out of her hiding-place and surveys the nest which 

 he has made for her. " He darts round her in every 

 direction, then to his accumulated materials for the nest, 

 then back again in an instant ; and as she does not ad- 

 vance he endeavors to push her with his snout, and then 

 tries to pull her by the tail and side-spine to the nest." ^ 

 The males are said to be polygamists ; ' they are extraor- 

 dinarily bold and pugnacious, while "the females are 

 quite pacific." Their battles are at times desperate ; " for 

 these puny combatants fasten tight on each other for sev- 

 eral seconds, tumbling over and over again, until their 

 strength appears completely exhausted." With the 

 rough-tailed stickleback ( G. trachurus) the males while 

 fitrhtincf swim round and round each other, biting and en- 

 deavoring to pierce each other with their raised lateral 

 spines. The same writer adds : * " The bite of these little 

 furies is very severe. They also use their lateral spines 



' Yarrcll, 'Hist, of British Fishes,' vol. ii. 1836, pp. 417, 425, 436. 

 Dr. Giinther informs me that the spines in R. clavata are pecuHar to the 

 female. 



' See Mr. R. Warington's interesting articles in ' Annals and Mag. of 

 Nat. Hist.' Oct. 1852 and Nov. 1855. 



* Noel Humphreys, 'River Gardens,' 1857. 



* Loudon's ' Mag. of Natural History,' vol. iii. 1830, p. 331. 



