ACKNOWLEDGMENTS 



To my friends, Dallas Lore Sharp, Mrs. Sylvester D. Judd, 

 and Miss Harriet E. Richards, I desire to express my deep ap- 

 preciation of their suggestions and criticisms. I am indebted to 

 Mr. James P. Chapin, Assistant-Curator at the American Museum 

 of Natural History, New York, for a critical reading of the 

 manuscript. 



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