36 REPTILES 



ancient cavern-dwellers. Such protective resemblance would be 

 of no use when in the darkness of the inner parts of the cave, 

 but many of these snakes are in the habit of taking up their 

 quarters on ledges near the entrance, from which they seize the 

 bats passing in and out. The cave-walls consist of yellowish 

 crystalline limestone traversed by blackish veins running in a 

 more or less nearly vertical direction. With these rocks the 

 colours and markings of the snake harmonise in a remarkable 

 manner, a blackish line along each side of the reptile's tail 

 simulating the veins in the rock. Young specimens have not 

 been found within the cave, and, if it really be that the species 

 breeds only in the open, the resemblance in colouring must be 

 due to fading in each individual. This snake is known as 

 Coluber tceniurus. It has also been discovered that an allied 

 member of the same genus — C. moellendorffi — takes up its 

 quarters in a cavern in Tonkin. Although the cave is of lime- 

 stone, the colouring of the snake is quite different from that of 

 the Malay species, the upper parts being grey with dark spots 

 and the tail ringed with red and black. Hence, it has been 

 argued, the resemblance of the Malay species to its surroundings 

 is accidental. 



As occupying a somewhat intermediate position between 

 the subject of haunts, or " station," and geographical distribu- 

 tion, reference may be made to the abundance of reptilian life 

 in certain so-called "oceanic" islands where mammals are al- 

 together unknown. The best instance of this is afforded by the 

 islands of the Galapagos group, off the west coast of South 

 America almost on the equator, which are tenanted by a 

 number of giant land-tortoises of the genus Testudo, as well as 

 by two large species of iguana, each representing a genus by 

 itself {Amblyrhynchus and Conolophus). Giant land-tortoises 

 also inhabited the Mascarene and theSeychelle islands till they 

 were more or less completely exterminated by man. 



It has been held that the Galapagos are truly oceanic 

 islands, that is to say, they have been raised from the ocean 

 without ever having formed part of a continent. 



But Dr. J. Baur, who visited the islands in 1890, wrote as 

 follows : — 



" In this case there must have been a time when not a 

 single organism existed on the islands. Only by accidental 



