72 NATURAL SELECTION in 



that reptiles furnish us with a very remarkable and instructive 

 case of true mimicry. 



Mimicry among Snakes 



There are in tropical America a number of venomous 

 snakes of the genus Elaps, which are ornamented with brilliant 

 colours disposed in a peculiar manner. The ground colour is 

 generally bright red, on which are black bands of various 

 widths and sometimes divided into two or three by yelloAv 

 rings. Now, in the same country are found several genera of 

 harmless snakes, having no affinity whatever with the above, 

 but coloured exactly the same. For example, the poisonous 

 Elaps fulvius often occurs in Guatemala with simple black 

 bands on a coral-red ground; and in the same country is 

 found the harmless snake Pliocerus equalis, coloured and 

 banded in identically the same manner. A variety of Elaps 

 corallinus has the black bands narrowly bordered with yellow 

 on the same red ground colour, and a harmless snake, Homa- 

 locranium semi-cinctum (Colubridae), has exactly the same 

 markings, and both are found in Mexico. The deadly Elaps 

 lemniscatus has the black bands very broad, and each of them 

 divided into three by narrow yellow rings ; and this again is 

 exactly copied by a harmless snake, Pliocerus elapoides, which 

 is found along with its model in Mexico. 



But, more remarkable still, there is in South America a 

 third group of snakes, the genus Oxyrhopus (Scytalidse), 

 doubtfully venomous, and having no immediate affinity with 

 either of the preceding, which has also the same curious 

 distribution of colours, namely, variously disposed rings of 

 red, yellow, and black ; and there are some cases in which 

 species of all three of these groups similarly marked inhabit 

 the same district. For example, Elaps mipartitus has single 

 black rings very close together. It inhabits the west side of 

 the Andes, and in the same districts occur Pliocerus eury- 

 zonus and Oxyrhopus petolarius, which exactly copy its 

 pattern. In Brazil Elaps lemniscatus is copied by Oxyrhopus 

 trigeminus, both having black rings disposed in threes. In 

 Elaps hemiprichii the ground colour appears to be black, with 

 alternations of two narrow yellow bands and a broader red 

 one ; and of this pattern again we have an exact double in 



