INTRODUCTORY REMARKS. 
THE system of classification followed. in this Catalogue is 
that proposed by Professor J. Dana, and adopted by him in his 
great work on the Crustacea of the U.S. Exploring Expedition 
under Commodore Wilkes (2 vols. 4to, 1852 and 1853, and 
Atlas). The characters of the families, sub-families, &c., are 
generally from his volumes, with such slight alterations and 
additions as seemed desirable for the purpose of this Catalogue. 
The descriptions of the genera and species are compiled from 
many different authors, the former being in part original, the 
latter often abbreviated or modified to ensure the necessary 
uniformity and accuracy throughout. 
Whenever the description of a species has been taken, either 
verbatim or in substance, from another author, this is indicated 
by the capital letters placed within brackets at the end of the 
description, which are the initials of the name of the author. 
It is scarcely necessary to refer here to all the authors whose 
works have been consulted; the principal, besides M. H. Milne 
Edwards and Prof. Dana, are, M. A. Milne Edwards, for the 
Brachywra, Mr. C. Spence Bate, F.R.S., for the Amphipoda, 
Dr. C. Heller, (Reise der Novara), M. de Haan, (Crustacea of 
the Fauna Japonica of Siebold), Mr. A. White, (in Dieffenbach’s 
