vi PREFACE 



of the Animal Kingdom (p. 289). The photograph of the midlarval 

 stage was kindly suppHed by Professor Sherman C. Bishop of the 

 University of Rochester. The upper figure is from G. K. Noble's 

 Biology of the Amphibia, courtesy of the McGraw-Hill Book Com- 

 pany (copyrighted, 1931). Figures 1, 2C, and 86-113 are reproduc- 

 tions of figures previously published by the author in the Journal of 

 Comparative Neurology and used here by courtesy of the Wistar In- 

 stitute of Anatomy and Biology, publishers of that Journal. The 

 other figures are originals prepared for this work. 



Money for the prosecution of the work and for financing its publi- 

 cation was liberally supplied by the Dr. Wallace C. and Clara A. 

 Abbott Memorial Fund of the University of Chicago. 



