PREFACE 



This revision of Linville and Kelly's Textbook in General 

 Zoology is issued under the joint authorship of Henr^ R. 

 Linville, Henry A. Kelly, and Harley J. Van Cleave. The 

 work of revising the material of the original book and the 

 selecting and organizing of new material has been carried 

 out by the junior author, with the cooperation and approval 

 of the senior authors. It has been the policy throughout 

 the revision to retain those distinctive features of method 

 of presentation and organization which have received such 

 general commendation and approval from teachers of 

 biology throughout the country who are familiar with the 

 earlier edition. 



The contents of this book have been selected and ar- 

 ranged as the basis for a full year's course in zoology for 

 students beginning the subject. In the revision of the 

 original edition an attempt has been made to give a dis- 

 tinct biological orientation of the subject. The possibility 

 of utilizing the text for the animal portion of a biological 

 course has been kept constantly before the authors. In a 

 course covering but a single semester or term, or in a bio- 

 logical course extending through the year, wide latitude of 

 choice is offered the teacher. 



The treatment of the phyla is in a descending order from 



the Arthropoda to the Protozoa, and in ascending order 



from the fishes to man. After many years of experience 



with classes of beginning students we believe that an order 



of this nature is likely to yield the best results. We do not 



deny that good results may be obtained by following what 



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