SNAKES. 115 



form by their burrowing habits, yet the species 

 included in the first-named family retain traces 

 enough of their former glories to show that 

 they are, to quote Dr Gadow, "undoubtedly 

 the last living descendants of formerly cosmo- 

 politan, rather archaic snakes." Even to-day 

 they have a wide distribution, occurring in 

 tropical and sub-tropical countries. The mouth 

 is exceedingly small, placed in the under surface 

 of the head, and the jaws are capable only of 

 the smallest dilatation. The tail, which is very 

 short, ends in a horny spine. 



The forms which make up the family Glauconidse 

 are interesting inasmuch as, though greatly de- 

 generate, the pelvic girdle and hind-limbs show 

 less reduction than in any other snakes, all the 

 elements of the girdle being represented, as 

 well as vestiges of femora or thigh bones. The 

 blind snakes feed on ants and millepedes. 



Just as some animals are omnivorous, whilst 

 others have become adapted to, or specialised for, 

 one kind of food, so others are omnimotile, if we 

 may use such an expression ; and now in one 

 direction, now in another, become pledged to 

 one form of locomotion only ; or, as we say, are 

 " specialised." We have already had many 

 instances of this, and the snakes furnish no 

 exception to the rule, though from their gener- 

 ally specialised conditions, further modifications 

 are neither striking nor profound. 



Instances of snakes which climb, crawl, and 

 swim, with equal ease, have already been 

 quoted ; so also have others, in which the body 

 has become adapted for one kind of locomotion 



