HERPETOLOGY. OP THE GRAND DUCHY OF BADEN. 143 



bearing on its origin ; nor can it be attributed to reversion, as in 

 the case of L. vivipara nigra. It seems rather to be a recently- 

 acquired coloration. With Zamenis viridiflavus the black, which 

 may be regarded as an accentuation of the normal brownish tint, 

 is attained by a series of imperceptible transitions, the speckled 

 immature markings — cf. the ontogeny of the Blackbird — lingering 

 longest about the head and neck. Viewed side by side, an adult 

 " carbonarius" and a young individual of the same species offer 

 an interesting study for the evolutionist. The tendency exhibited 

 by many Colubrine Snakes to uniformity of coloration, which 

 has led to the abolition of the brighter immature patterns and 

 markings, has here and in some analogous instances proceeded, 

 apparently, a step too far. It may be doubted whether the 

 apparent advantages which a uniform tint would confer are now 

 gained, and it remains a matter of speculation what the purpose 

 of this innovation may consist in. In spite of some evidence of 

 a similar nature,* I am disinclined to call to aid the cumulative 

 effects of female preference, for it can hardly be supposed that a 

 simultaneous and almost identical change of aesthetic tastes 

 should be taking place in many of the females of several distinct 

 species. And the fact that this form of coloration is most 

 strongly pronounced in the oldest male seems sufficient to 

 account for its successful debut, since in all probability this new 

 variety — whatever its original " cause " and present advantages — 

 will, as such, possess greater vigour and fertility. The few well- 

 known cases of melanism briefly referred to will serve to show 

 that the causes producing this condition are in Herpetology no 

 less obscure than in other departments of Zoology, and that, like 

 albinism, it may still be called a dark chapter in Biology. It is 

 less commonly accompanied by pathological symptoms than 

 albinism in its various forms, whether innate or acquired. 

 Indeed, the only case in Herpetology of melanism occurring 

 (perhaps) as a disease which I have met with was a Triton 



* Poulton, ' Colours of Animals,' p. 303. It has also struck me that the 

 " carbonarius" variety of this species is even more lively than the older 

 form, but its extreme wariness may be due to the instinctive knowledge that 

 the black colour renders it more conspicuous. And perhaps for this very 

 reason it has not been more universally adopted by other snakes who 

 equally incline to this coloration, but who are inferior to Zamenis in point 

 of agility. 



