iv PREFACE. 



atory 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 al- 

 lotted 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 properly 

 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 2 and 127 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. 



