REVISER’S NOTE. 
In this revision of Professor Orton’s work only such 
changes have been introduced into the text as have been 
made necessary by recent progress in Zoology. Some 
errors of statement have been corrected, and the classifica¬ 
tion has been slightly changed. The principal addition 
consists of an Appendix composed of directions and sug¬ 
gestions for the performance of simple physiological ex¬ 
periments, and for the examination of certain animals 
representative of the more important groups. These ex¬ 
periments and dissections are so elementary that they may 
easily be performed by either teacher or pupil. Very 
little apparatus, few instruments, and no special skill are 
required. The Appendix is designed to make the book of 
more practical value than formerly, and thus adapt it to 
the laboratory rather than the literary method of teach¬ 
ing. 
An asterisk at the head of the chapter indicates that its 
subject-matter may be illustrated by practical work, for 
which directions will be found in the Appendix. 
University of Rochester. 
Charles Wright Dodge. 
