20 WATER REPTILES OF THE PAST AND PRESENT 



specimens of fossil animals, and especially 

 of fossil reptiles, to preserve all parts of 

 the skeleton, so far as possible, in the 

 relations they occupied in the rocks until 

 they can be studied in the laboratory. 

 Many grievous errors have been made in 

 the past by hasty inferences from fragmen- 

 tary and poorly collected specimens. 



Because of the reliance which must be 

 placed upon the skeleton it will be neces- 

 sary to speak somewhat in detail of its 

 structure in the reptiles, and to use not 

 a few terms in its description that are 

 unfamiliar to the general reader. So far as 

 possible technical terms will be avoided, 

 though some must be used, as there are 

 no equivalents in the English language 

 for them. The reader may use this 

 chapter as a sort of explanatory index 

 or glossary for the better elucidation of 

 the necessary details of the following 

 chapters. 



It is needless to say that the skeleton of 

 a reptile is arranged on essentially the 

 same plan as that of our own; the bones 

 have the same names that they have in 

 our own skeleton, but there are more of 

 them, and the individual bones, as a 

 general rule, are less highly specialized, 

 that is, are not so well adapted for special 

 functions. In a word, the skeleton of a 

 reptile for the mcst part is generalized, 

 though particular parts may be highly 

 specialized for particular uses. As a rule, 

 if not as a law, the course of evolution 

 has been to reduce the number of parts 

 and to adapt those which remain more 



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