PREFACE V 



Professors A. S. Packard, J. H. Comstock, H. H. Wilder, J. I. 

 Hamaker, Frank Smith, H. B. Ward, E. L. Rice, H. L. Osborn, 

 H. L. Clark, C. W. Hargitt, and H. S. Jennings. Their criti- 

 cisms and suggestions have been most helpful and important, 

 and I wish to acknowledge a heavy obligation to each of them. 



H. S. PRATT 

 Haverford, Pa. 



October, 1901 



PREFACE TO THE REVISED EDITION 



The principal differences between the first and second editions 

 of this work consist in the addition of several dissections in the 

 second edition, and the revision of the scheme of classification in 

 the Appendix. The additional dissections are those of the house 

 fly, a spider, the oyster, a sea cucumber, Gonionemus, and a sea 

 anemone. 



Haverford, Pa. 

 June, 1915 



