vi PREFACE. 



chose at last a stone so monumental in form 

 that not a touch of the hammer was needed 

 to fit it for its purpose. In conclusion I allow 

 myself the pleasure of recording here my grat- 

 itude to him and to all who have aided me 

 in my work. 



ELIZABETH C. AGASSIZ. 



Cambridge, Mass., June 11, 1885. 



