84 ON THE THYSIOGNOMY OF SERPENTS. 



law, that the younger the individual the more vivid are the 

 colours, and more distinct in their distribution ; and often 

 the tints which adorn the young are effaced in the old, or 

 they become absolutely uniform ; for instance, in the Colu- 

 ber canus, C. melanurus, the Homalopsis buccata, the 

 Xenodon severus, and others. 



The faculty of spontaneous change of tint, — a faculty 

 which many Batracliians, a great numljcr of Saurians, and 

 particularly Cameleons, possess, — is only observed in an 

 inferior degree among Ophidians, and that principally among 

 the climbing serpents distinguished by their green colour. 

 The differences which exist between the relative colours 

 of the male and female, and the changes produced in either 

 sex at the principal periods of life, have been little studied. 

 Sometimes, as in the Tropidonotus Natrix, tlie two sexes 

 perfectly resemble each other ; but this is not the case in 

 the Common Viper, in which the markings of the female un- 

 dergo successive changes before the individual attains the 

 term of its full growth ; whilst the males on coming out of 

 the egg, present tints analogous to those of the adult of the 

 same sex. 



We have spoken above of tlie gi-eat influence exercised 

 by the casting of the skin on the beauty of the original tints. 

 The changes which it produces are so much more worthy 

 the attention of the naturalist, that the moult operates by 

 insensible degi'ees, and takes place several times in the 

 year. 



It happens almost constantly that the tints of Ophidians 

 arc effaced in a great measure after death, or that, when ex- 

 posed to the action of ardent spirits, they suffer changes 

 more or less marked. The black, the brown, the ochre- 

 yellow, and many other such colours, do not, however, al- 

 ways lose even the lustre reflected by the uniform surface 

 of the scales ; among the number of the species which re- 

 tain their colours after death, are the Calamaria arctiventris, 

 C. Brachyorrhos, the Tortrix maculata, the Xenopeltis, the 

 Coronella rufula, the Lycodon Hebe, and L. subcinctus, 

 the Coluber Constrictor, C.^sculapii, C. melanurus, several 

 species of Naja, Homalopsis, Vipera, and a gi-eat many 



