INTRODUCTION. 
xm 
These species were, at this date, mostly published without illustration, but 
figures of these . and a few additional Devonian species were given in the 
Illustrations of Devonian Fossils, in 1876. 
The following authors have published descriptions or notices of the American 
Devonian Trilobites, and full reference to their works will be found under the 
generic and specific synonymies: 
Harris, 
Conrad, 
Billings, 
Eaton, 
Brongniart, 
Emmons, 
Burmeister, 
Green, 
Castelnau, 
Hall, 
Clarke, 
Kayser, 
Meek, W alcott, 
Nicholson, Whitfield, 
Owen, Williams, H. S., 
Shumard, Williams, S. G., 
Yanuxem, Worthen. 
^Vogdes, 
The other orders of the Crustacea have only more recently attracted the 
attention of American writers. The Xtphosura have been discussed by Wil¬ 
liams and Packard; the Eurypterida, by Hall and Claypole; the Phyllocarida, 
by Hall, Whitfield, Clarke, Packard, Beecher, Woodward and Jones; the 
Decapoda, by Whitfield; the Phyllopoda, by Clarke, Packard and Jones; and 
the Cirripedia, by Whitfield and Clarke. 
II. Classification. 
In the discussions of the species, it has not seemed advisable to accord a 
strict adherence to any given system of classification. The Trilobites, which 
include the larger and, for the geological student, the most important part of 
the work, stand first in order of treatment; the other orders of the sub-class 
to which they belong, being considered in the latter portion of the work. In 
the introductory discussion of the genera the same order is followed. 
The classification which has been adopted, with modifications, for the purpose 
of the work, is the following; 
* It is understood that a “Bibliography of the Palseozoic Crustacea,” by Lieut. Vogdes, is ready for press 
at the present writing. 
