68 



THE GEOLOGICAL EVIDENCES 



special modification of a certain organ or structure 

 can be found than that exemplified in the develop- 

 ment of the deer's horn. Everyone is aware that 

 in our ordinary deer with branched antlers the 

 process of growth is a regular and successive 

 one. Before the first shedding we have a single 



Successive stages in the development of the stag's antler. 

 (After Gaudry.) 



solid horn ; after this shedding a single tine is 

 developed ; then a second, and a third, until we 

 have the complicated structure of the typical ant- 

 ler. Now, precisely this system of progression 

 can be traced in the geological history of these 



