CHAPTEE IX 



fossils, keys, etc. 



Amphibians of the Far Past 



Except the csecilians, living amphibians are far 

 away from the old fossil forms which had such 

 peculiar teeth (usually), strong armors, and bony 

 skulls. Perhaps they became so stiif and awkward 

 that they could not escape from their enemies ; or they 

 may have become so inflexible in their structure that 

 they could not change, as the conditions of the air 

 and earth changed, and hence they perished. 



The csecilians, as noted, have something of scales 

 and style of skull which was formerly fashionable. 

 Their burrowing habits may have saved them, and 

 the very humble habits of our little denizens of the 

 slime may have preserved them also. Many connect- 

 ing links between these and modern forms have per- 

 ished. There seems to be no form yet found that 

 stands between the frog-forms and the tailed forms 

 of to-day ; nor between either and the ca^cilians. No 

 salamander leaps much ; no frog has a vestige of a 

 tail outside of the body when grown. In their baby- 

 hood only the two groups come close together. As 

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