AUSTRALIAN SNAKES. 13 



much affected in sight ; the actual operation, as far as 

 the head is concerned, when once commenced, was 

 always speedy. 



Locomotion. 



Locomotion is usually associated with certain 

 external organs specially adapted for such purpose, as 

 arms, legs, wings, fins, etc. Snakes, however, have 

 none of these, and to those unacquainted with their 

 anatomy, the rapid movements are difficult of ex- 

 planation. Pliny, *' the wisest of men," admitted that 

 the actions of serpents were beyond his comprehension. 

 Snakes have an enormous number of vertebra3, or bones 

 in the back, most of which (the exceptions being portion 

 of the tail bones) carry each a pair of ribs. Each pair 

 IS attached below to one of the broad, transverse ventral, 

 or belly plates, and it is mainly by means of such plates 

 that the snake moves. The free edges of these plates 

 are directed backwards, and catch the slightest pro- 

 jection of the ground : while a portion of tlie body is 

 thus held, a part in front is thrust out and similarly 

 attached, the hinder portion is next drawn forward. 

 If this was all, the effect would be identical with the 

 progression of a worm, and would need a telescopic 

 power which the plates do not possess. It is well-known 

 that the track of a snake is sinuous, and the motion lias 

 been thus described by Dr. Giinther : — *' Although 

 their motions are in general very quick, and may be 



