FISHES. 327 



CHAPTER XII. 



SECONDARY SEXUAL CHARACTERS OF PISHES, AMPHIBIANS, 

 AND REPTILES. 



Pishes: Courtship and battles of the males— Larg-er size of the females 

 — Males, bright colors and ornamental appendages; other strange 

 characters— Colors and appendages acquired by the males during 

 the breeding-season alone— Fishes with both sexes brilliantly colored 

 — Protective colors — The less conspicuous colors of the female can- 

 not be accounted for on the principle of protection— Male fishes 

 building nests, and taking charge of the ova and young. Amphib- 

 ians: Differences In structure and color between the sexes— Vocal 

 organs. Reptiles: Chelonians— Crocodiles — Snalces, colors in some 

 cases protective — Lizards, battles of— Ornamental appendages — 

 Strange differences in structure between the sexes— Colors— Sexual 

 differences almost as great as with birds. 



We have now arrived at the great sub-kingdom of the Ver- 

 tebrata, and will commence with the lowest class, that of Fishes. 

 The males of the Plagiostomous fishes (sharks, rays) and of 

 ChimEerold fishes are provided with claspers which serve to retain 

 the female, like the various structures possessed by many of the 

 lower animals. Besides the claspers, the males of many rays 

 have clusters of strong sharp spines on their heads, and several 

 rows along "the upper outer surface of their pectoral fins." These 

 are present in the males of some species, which have other parts 

 of their bodies smooth. They are only temporarily developed 

 during the breeding-season; and Dr. Giinther suspects that they 

 are brought into action as prehensile organs by the doubling in- 

 wards and downwards of the two sides of the body. It is a re- 

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

 cies, as of Raia clavata, have their backs studded with large hook- 

 formed spines.' 



The males alone of the capelin (Mallotus villosus, one of Sal- 

 monid83), are provided with a ridge of closely-set, brush-like 



1 Tarrell's 'Hist, of British Fishes,' vol. ii. 1836, pp. 417, 425, 436. Dr. 

 Gunther informs me that the spines in R. clavata are peculiar to the 

 female. 



