PEEEACE. 
In the following pages I have adopted in great part 
the general arrangement of M. Milne Edwards, and have 
adhered almost exclusively to the terminology used by 
him in his classic work on the Crustacea. Some com- 
parative anatomists may object to many of the terms 
employed as not agreeing with their ideas of Homo- 
logies ; but I have preferred using terms sanctioned by 
an authority such as M. Milne Edwards, though perhaps 
in some cases erroneous, to devising others which might 
be liable to the charge of still more serious mistakes. 
With few exceptions, the figures of the species of the 
Branchiopoda and Lophyropoda have been drawn from 
living subjects either by myself or by Mr. Wing, who 
has devoted much time and labour in illustrating this 
work. Those of the Caligidae and Lerneadae have been 
done by Mr. Wing exclusively, and from specimens 
preserved in spirits, most of which have been kindly 
placed in my hands for the purpose by W. Thompson, 
Esq., of Belfast, to whose liberality I have much pleasure 
