300 



A HISTORY OF FISHES 



throughout the Hfe of the fish, becomes much more intense as 

 the spawning season draws near. 



Differences in the form of the fins are nearly as common 

 among fishes which indulge in pairing or courtship as differences 

 in coloration, those of the male always being larger and more 

 brightly marked. In many Cichlids and Cyprinodonts some of 



Fig. 1 09. — SECONDARY SEXUAL CHARACTERS. 



A. Male and female of the Common Dragonet {Callionymus lyra) ; b. Female, 



and head of male of Bothus podas ; c. Male, and heads of male and female of 



Mailed Cat-fish {Xenocara occidentalis) . All X about -3. 



the rays of the dorsal and anal fins may be prolonged to form 

 fine streamers, and the membrane provided with eye-like spots 

 of red, blue, or yellow. In some of the Mailed Cat-fishes 

 {Loricariidae) the sexual differences are even more marked, 

 affecting the shape of the snout, the form of the mouth and 

 lips, the development of bristles on the head and fins, or of 

 fleshy tentacles on the snout (Fig. logc). In the Scald-fish or 

 Lantern-fish (Arnoglossus) , and in some other Flat-fishes, the 



