Unless otherwise indicated, all of the illustrations in this vol- 
ume are from photographs taken by Maurice Ricker, official 
photographer of the expedition. 
The author is under great obligation to Professor H. F. Wick- 
ham for his patience and care in reading the proof of this 
volume. 
C. C. Nurtine 
University of Iowa, 
May 5th, 1919 
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