SEXUAL SELECTIOX. 
CHAPTER XII. 
Secondary Sexual Characters of Fishes, Amphibians, 
AND KePTILES. 
Fishes: Courtsliip and battles of the males — Larger size of the 
females — Males, bright colours and ornamental appendages; 
other strange characters — Colours and appendages acquired by 
the males during the breeding-season alone — Fishes with both 
sexes brilliantly coloured — Protective colours — The less con- 
spicuous colours of the female cannot be accounted for on the 
principle of protection — Male fishes building nests, and taking 
charge of the ova and young. Amphibians : Differences in 
structure and colour between the sexes — Yocal organs. Eep- 
TiLES : Chelonians — Crocodiles — Snakes, colours in some cases 
])rotective — Lizards, battles of — Ornamental appendages — 
Strange differences in structure between the sexes — Colours 
— Sexual differences almost as great as with birds. 
We have now arrived at the great sub-kingdom of the 
Yertebrata, and will commence with the lowest class, 
namely Fishes. The males of Plagiostomous fishes 
(sharks, rays) and of Chimaeroid fishes are provided 
with claspers which serve to retain the female, like the 
various structures possessed by so 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 the other parts of their bodies 
VOL. II. B 
