360 NATURAL HISTORY. 



626. With these general plans there is in every animal 

 a marked relation of each part to every other part. Ev- 

 ery bone, for example, not only has its exact relation to 

 every other bone, but also to every other part and organ. 

 It is from this harmony existing in every animal frame 

 that the zoologist is able to know the general structure 

 and habits of an animal on inspecting a single bone or 

 tooth belonging to it. For example, suppose that he 

 picks up a tooth with two stout roots and a sharp cutting 

 edge rising to a point, such as you see in Fig. 275. Let 



us see what he can know in regard to the 

 animal to which this tooth belonged. First 

 he would know that it was a Vertebrate, 

 for no teeth at all like this are ever found 

 m an anmia l outside of the Vertebrate class- 

 es. He knows, therefore, that this animal 

 had a brain and spinal marrow, that its 

 rig. 275. senses were well developed, and that its 

 blood was red. Then the two long roots show that the 

 tooth was deeply implanted in a double socket, and that 

 the animal was, therefore, a Mammal, for this arrange- 

 ment is seen only in that class. The cutting edge of the 

 crown indicates that the animal was a carnivorous quad- 

 ruped, and that its jaws moved upon each other with a 

 scissors-like motion ( 67), and not a grinding one, as in 

 the herbivorous quadrupeds. It may be inferred, also, 

 that the feet were not hoofed, but armed with claws for 

 securing the prey, and that the muscles both of the limbs 

 and head were very strong. The general shape of the 

 animal ( 70) can also be made out, and its size can be 

 estimated from the size of the tooth. The kind of stom- 

 ach which it had can also be known ( 68). Baron Cu- 

 vier had great skill in such studies. From a single bone, 

 or even a piece of one, he could picture an entire skele- 

 ton, and describe the character and the habits of the an- 

 imal. 



627. The general plans adopted by the Creator should, 



