PREFACE 



who read the manuscript and gave many valuable suggestions; 

 Dr. Leonhard Steineger of the National Museum at Washington 

 who not only allowed study of the National Museum Collection 

 of Salientia but also gave assistance in the identification of speci- 

 mens; and Miss Maud Slye, Instructor in the Rhode Island 

 Norm.al School, Providence, who read the manuscript from the 

 standpoint of its English. 



Thanks aie due to many others also, for help In getting 

 living material, for opportunities for study and so on. Among 

 these are Dr. Frank R. Lillie, University of Chicago; Dr Wm. 

 M. Wheeler, American Museum of Natural HistOiy, New York; 

 Dr. Hans Gadow, University of Cambridge, England; Director, 

 C. H. Townsend, New York Aquarium; Dr. A. D. Mead, Brown 

 University, Providence; Dr. J. Van Denburgh, California Acad- 

 emy of Science, San Francisco; and Dr. J. F. Illingworth, Seattle, 

 Washington. 



It is hoped that the book not only will introduce the v,le- 

 mentary nature student to the fascinations of pond life but that 

 it will suggest to the more advanced student serious work on the 

 classification, life histories and habits of the North American 

 Salientia — for there remains a field of work of such breadth that 

 what has been done seems only a beginning. 



Mary C. Dickerson 



Providence, R. I. 

 June lo, 1906. 



