TERRESTRIAL VERTEBRATES 363 



fins. This is the only clue, and a very inadequate one, to the manner 

 in which feet developed out of fins. It has, however, been suggested 

 that the fin rays might have been reduced in size and number and the 

 basal bones of the fin rearranged (Fig. 246). Thus an appendage was 

 formed which came to possess five digits, the typical number in the 

 amphibian limb. 



