PREFACE. 
The principal object of the present Catalogue is to give a 
complete List of the Crustacea, with descriptions of all 
the genera and species known to exist, indicating at the 
same time, by a B.M. in the margin, those contained in the 
British Museum. When the specimen is not to be seen 
in that Collection, a reference is made to the Cabinet from 
whence the description -was obtained. 
For fuller descriptions and figures of the new' genera and 
species in this Part of the Catalogue, the student is re¬ 
ferred to the Twenty-first volume of the Transactions of 
the Linnean Society. 
JOHN EDWARD GRAY. 
1 December, 1855. 
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