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PREFACE TO SECOND EDITION 



The present edition represents a revision of certain parts of sev- 

 eral chapters, such as those dealing with Annelida, Genetics, Eugenics, 

 Internal Regulation and Endocrines, Physiology, and Phylogenetic 

 Relations of Animals. A brief section on Mammalian Development 

 has been added. Numerous minor corrections or improvements have 

 been made throughout. Several illustrations have been added and 

 others improved. 



In addition to the acknowledgements included in the preface to the 

 first edition, the author wishes to acknowledge the help of Dr. 

 Kelshaw Bonahm of the Fish and Game Department, Agricultural and 

 Mechanical College of Texas, on the chapter dealing with Pisces. 

 At this point recognition is made of assistance given by Mr. Gordon 

 Gunter in revising the list of animals of the Texas Gulf Coast in the 

 chapter on ]\Iarine Zoology. The author is also indebted to Dr. Fred 

 L. Kohlruss, Biology Department, University of Portland (Oregon), 

 for numerous useful suggestions. Many valued suggestions have 

 been received from individuals in a number of other institutions where 

 the first edition has been in use. The author's indebtedness and 

 appreciation is also expressed to Mr. Phil T. Williams who has 

 furnished a number of the new illustrations. Finally, appreciation is 

 expressed to Agricultural and Mechanical College of Texas for co- 

 operation in numerous ways to assist in making this revision. 



George E. Potter. 

 College Station, Texas 



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