1 78 SNAKES, 



its twofold virtues of mouser and 'rat-tail' catcher, is 

 domesticated and petted in some of the islands.^ 



In many of the Colubrine snakes it is almost impossible 

 to distinguish where the ribs cease and the tail begins, except 

 by the anus, so very gradually does the body taper. Nor 

 does there appear to be any certain rule about the length 

 of tails, which in some snakes are even longer than their 

 bodies, and in others not one-tenth the length. 



In giving the length of a few snakes (not in feet or 

 inches, but in the number of their vertebrae), the reader 

 will obtain a clear idea of this variation in tails. One 

 species of rattlesnake has 194 vertebrae, of which 168 support 

 each a pair of ribs, leaving 24 for its tail, or one-eighth. 

 The python has 291 vertebrae, of which the 3d to the 251st 

 support a pair of ribs, leaving 40 for its tail, or less than 

 one-seventh of its length. 



Let me explain a seeming discrepancy of arithmetic. 

 The spine of the boa constrictor consists of 304 vertebrae, 

 of which 2 next the head support no ribs, and 252 support 

 each a pair of ribs. Taking away the first two, which, 

 having no ribs, may be said to form the neck of the snake, 

 that leaves fifty joints for the tail, or about one-sixth of 

 the entire length. Our little sums, therefore, are as follows, 

 in reckoning the vertebras : — 



RATTLESNAKE. BOA CONSTRICTOR. PYTHON. 



Neck, ... 2 Neck, ... 2 Neck, . . 2 



Supporting ribs, 168 Supporting ribs, 252 With ribs, 249 



Tail, .... 24 Tail, .... 50 Tail, . . 40 



Total, 194 Total, 304 Total, 291 



^ Dr. A. Stradling affirms that these two snakes do not invariably molest each 



