VI PREFACE TO THE FIRST EDITION. 



which have been used can be purchased of dealers in 

 laboratory supplies (see Introduction) at a cost of less 

 than sixty cents per pupil. In the second place, the 

 number of forms studied and the extent to which details 

 of structure are worked out must be such that the work 

 outlined can be done by students of average ability, in 

 the time usually allotted to such work in the ordinary 

 course. Especial care has been taken that time shall 

 not be wasted in working out features of no morphological 

 importance. Counting tail-feathers or fin-rays has no 

 place in elementary zoology. 



Again, the work has been made largely macroscopic in 

 character. Microscopes are expensive, and many institu- 

 tions feel that they cannot afford to provide each student 

 with one of these instruments. Then, too, there are 

 enough important facts to be discovered with scalpel and 

 hand-lens. Too many beginners have been lost among 

 cell-theories and drowned in staining-fluids. These prop- 

 erly come after the elements of the study have been 

 mastered. 



In order of treatment the author has followed the se- 

 quence which he believes productive of the best results- 

 A strictly logical course would lead from the simple to the 

 complex, but in practice this has not been found as valu- 

 able as the order adopted here. 



A number of illustrations have been prepared especially 

 for this work. Most of the others are credited to the 

 author from which they are taken. It may interest some 

 to know that Figures 39 and 123 were engraved for the 

 second part of Agassiz and Gould's " Principles of Zool- 

 ogy/ which was never published. 



TUFTS COLLEGE, MASS., June 14, 1897. 



