PREFACE. 
THE plan of this work is so fully explained in the 
Introductory Chapter that but little preface is needed. 
Its main object is to acquaint young people with the 
structure and habits of the lower forms of life ; and 
to do this in a more systematic way than is usual in 
ordinary works on Natural History, and more simply 
than in text-books on Zoology. 
For this reason I have adopted the title " Life 
and her Children," to express the family bond uniting 
all living things, as we use the term " Nature and her 
Works," to embrace all organic and inorganic pheno- 
mena ; and I have been more careful to sketch in 
bold outline the leading features of each division, 
than to dwell upon the minor differences by which it 
is separated into groups. 
I have made use of British examples in illustration 
wherever it was possible, and small specimens of most 
