PREFACE TO THE SECOND EDITION. 
THE present Edition has been enlarged and altered so as 
to correspond, in most respects, with the American Edition, 
published in 1871. The series of questions appended to 
the latter has, however, been dispensed with here, and will 
be found in the “ Examinations in Natural History,” which 
has been recently prepared by the Author, and which con- 
tains a progressive series of questions adapted to his 
Introductory and Advanced Text-books, and to his Stu- 
dents’ Manual of Zoology. A few additional illustrations 
have also been added where they appeared to be desirable. 
UNIVERSITY COLLEGE, TORONTO, 
October 1, 1872. 
