224 REPTILES

of limbs is no guide to classification, inasmuch as there
are fishes without limbs, and amphibians without
limbs, and even lizards without limbs. Asa matter of
fact, too, the pythons have rudimentary hind legs. A
snake is very much of a vertebrate—in some species
there are 400 vertebre—and so quick is he in
the use of his ribs that, as Sir Richard Owen says,

   

    
   

     

      

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SKELETON OF A PYTHON

‘he can outclimb the monkey, outswim the fish, out-
leap the zebra, outwrestle the athlete, and crush the
tiger. This mode of rib progression is not difficult
to understand. ‘When a part of their body,’ says
Mr. Boulenger, ‘has found some projection of the
ground which affords it a point of support, the ribs,
alternately of one and the other side, are drawn more