ILLUSTRATIONS AND ACKNOWLEDGMENTS 



The colored plates are photographed from specimens loaned by The 

 Chicago Academy of Sciences, and have been previously published in 

 "Birds and Nature," Volumes VII, IX, and XII. The full-page half- 

 tones are from negatives by Mr. Frank M. Woodruff, Mr. T. H. Purple, 

 and Professor Alja R. Crook. A number of the line engravings and 

 several of the half-tones in the text are from the works of Try on, Wood- 

 ward, Binney, Dall, Verrill, Morse, Prime, Lankester, Brooks, Hyatt, 

 Gould, Goode, and Kimz. Several of these have been published in the 

 Bulletins and Reports of the United States Fish Commission. Acknowl- 

 edgment is made for these severally in the descriptions of each illustration. 

 To these volumes the author desires to express his indebtedness, and also 

 to The Chicago Academy of Sciences for the loan of various cuts which 

 appeared in " The Mollusca of the Chicago Area." When not otherwise 

 stated, the line engravings were from drawings made by the author 

 especially for this work. 



The nomenclature used is mainly that of Dr. William H. Dall, of the 

 United States National Museum, and Dr. Henry A. Pilsbry, of the 

 Academy of Natural Sciences of Philadelphia. 



XVll 



