PKEFACE 



This work has been written for the use of individual students, 

 as well as for classes in schools and colleges. No similar work 

 on the snail has been published in this country, and in my own 

 investigations I have seriously felt the need of one. 



I have endeavored to write a work which will enable the stu- 

 dent, without a previous knowledge of the subject, satisfactorily 

 to pursue his investigations. I have, therefore, commenced at the 

 beginning, giving explanations in regard to the instruments 

 necessary, methods of dissection, how to collect the animals, etc., 

 followed by a plain, but full, description of all the organs, with- 

 out the use of too many technical terms, and unencumbered by 

 theories. 



I have made very full illustrations of all the organs and parts 

 of organs, enabling the student at once to see their form and po- 

 sition. These illustrations are accurate copies from nature and 

 in no case are they diagrammatic. 



The manuscript of that portion of this work treating of anat- 

 omy and physiology was kindly reviewed by Prof. H. A. Pilsbry, 

 of Philadelphia, and to him I am indebted for suggestions, spe- 

 cially in regard to nomenclature. I am also indebted to Prof. 

 E. G. Conklin, of the University of Pennsylvania, who reviewed 

 that portion treating' of the embryology of L i m a x . 



George B. Simpson 



