Chap. XII. FISHES. 9 



of the dorsal fin.. The young males resemble in struc- 

 ture and colour the adult females. Throughout the 

 genus Calh'onymus/*^ the male is generally much more 

 brightly spotted than the female, and in several species, 

 not only the dorsal, but the anal ^n of the male is much 

 elongated. 



The male of the Cottiis scorpius, or sea-scorpion, is more 

 slender and smaller than the female. There is also a 

 great difference in colour between them. It is difficult, 

 as Mr. Lloyd ^^ remarks, " for any one, who has not seen 

 " this fish during the spawning-season, when its hues are 

 " brightest, to conceive the admixture of brilliant colours 

 " with which it, in other respects so ill-favoured, is at 

 "that time adorned." Both sexes of the Lahrus mixtus, 

 although very different in colour, are beautiful ; the male 

 being orange with bright-blue stripes, and the female 

 bright-red with some black spots on the back. 



In the very distinct family of the Cyprinodontidse — 

 inhabitants of the fresh waters of foreicfu lands — the 

 sexes sometimes differ much in various characters. In 

 the male of the Mollienesia petenensis,^"^ the dorsal fin is 

 greatly developed and is marked with a row^ of large, 

 round, ocellated, bright-coloured spots ; whilst the same 

 fin in the female is smaller, of a different shape, and 

 marked only with irregularly-curved brown spots. In 

 the male the basal margin of the anal fin is also a little 

 produced and dark-coloured. In the male of an allied 

 form, the Xipho]j]iorus Hellerii (fig. 29), the inferior 

 margin of the anal fin is developed into a long filament. 



^- ' Catalogue of Acantli. Fishes in the Biitish Museum,' by Dr. 

 Giinther, 1861, p. 188-151. 



1^ 'CJame Birds of Sweden,' &c., 1867, p. 466. 



^"* With respect to this and the following species I am indebted to 

 Dr. Giinther for information : see also his paper on the Fishes of 

 Central America, in ' Transact. Zoolog. Soc.' vol. vi. 1868, p. 485. 



