THE GREAT GROUPS OR "QRDERS"' 71 



— the muscle inside of us wliieli liiccouglis — helps to 

 force the breath out ; and the reptiles have the honor 

 of introducing this muscle also. In serpents there is 

 no breast-bone, but a great array of long ribs, that 

 almost encircle the body, hel]3 them to breathe. The 

 reptiles also, through the crocodiles only, brought in 

 the first four-chambered heart, and hinted first of hot 

 blood. Thus have all the creatures shown their prog- 

 ress by their breathing and circulation. We shall 

 see that some other things came in first with the rep- 

 tiles, but we shall note them later. This little pre- 

 view is given that we may know why we should be 

 interested in this class — a class which in its backward 

 ties and upward outlook has no equal. 



The Great Groups or " Orders " 



As we glance at the living (not extinct) reptiles 

 they seem, like the amphibians, to be divided by their 

 forms into three great groups : First, the tortoise- 

 forms ; second, the lizard-forms ; and third, the ser- 

 pent-forms. But this will not hold with the scientist 

 — except in the case of the tortoise-forms. He tells 

 us that the crocodiles, though lizard like in shape are 

 far from being so in structure, and really a much 

 older family ; that another lizard -shaped creature in 

 New Zealand {Sphenodon^ Tuatera or Ilatterici) ac- 

 tually belongs to one of the old families further back 

 still, and that there is considerable doul)t whether 

 lizards and serpents should be separated at all, since 

 some snakes have rudiments of legs and some lizards 

 have none at all. He would even hint that the 

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