SEXUAL SELECTION. 
Part II. 
sraootb. They are only temporarily developed during 
the breeding-season ; and Dr. Gunther suspects that they 
are brought into action as prehensile organs by the 
doubling inwards and downwards of the two sides of the 
body. It is a remarkable fact that the females and not 
the males of some species, as of Raia 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 (Gasterosteiis lei- 
urus) has been described as mad with 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 ma- 
terials for the nest, then back again in an instant ; 
and as she does not advance he endeavours 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 extraordinarily bold and 
pugnacious, whilst the females are quite pacific.” 
Their battles are at times desperate ; for these puny 
combatants fasten tight on each other for several 
seconds, tumbling over and over again, until their 
'' strength appears completely exhausted.” With the 
rough-tailed stickleback (G. trachurus) the males whilst 
fighting swim round and round each other, biting and 
endeavouring to pierce each other with their raised lateral 
spines. The same writer adds,^ the bite of these little 
1 Yarrell’s ‘ Hist, of British Fishes,’ vol. ii. 1836, p. 417, 425, 436. 
Dr. Giinther informs me that the spines in B. clavata are peculiar to the 
female. 
2 See Mr. K. Warington’s interesting articles in ‘Annals and Mag. 
of Nat. Hist.’ Oct. 1852 and Nov. 1855. 
^ Noel Humphreys, ‘ Kiver Gardens,’ 1857. 
‘ Loudon’s ‘ Mag. of Natural History,’ vol. iii, 1830, p. 331. 
