PREFACE. 
Tue rapid progress made in the advancement of the various 
Sciences, especially that of Geology, and its important branch 
of Paleontology, has necessitated, for instructive purposes, such 
a condensation of details, as may simplify the subject to the 
Students of that Science. 
With this object the present work was projected, its design 
being to exhibit to the eye such fossils only as are considered 
characteristic of the principal groups or formations of the stra- 
tified rocks; requiring, necessarily, considerable judgment in 
their selection, from the large number now known, as well as 
truthfulness in depicting them; the author’s long experience, 
and personal execution of the plates, may be considered a sufti- 
cient guarantee for their correctness. The descriptive remarks 
on the groups of fossils, with Woodcut Illustrations, is an ad- 
ditional part of the work not originally intended, but it is 
hoped this portion, with the aid of the excellent Wood En- 
gravings by Mr. William Oldham, of recent and fossil forms, 
for comparison, will add to its clearness and utility. 
It is a matter of regret that so long a time has elapsed be- 
tween the publication of the first part and the conclusion of 
the Volume ; this has arisen from various causes, over which the 
Author had no control. 
This Volume has been made to complete the Paleozoic di- 
vision of strata by the addition of two extra plates. It thus 
contains forty-two Lithographic plates, comprising more than 
700 figures of fossils, over 300 of these being original. The de- 
scriptive remarks are illustrated by eighteen Wood Engravings, 
including fifty-eight figures. All the figures are of the natural 
size, except where otherwise mentioned, the subjects being ar- 
ranged as far as practicable, zoologically, as well as strati- 
graphically. 
Although complete in itself as far as the Paleeozoie division 
extends, this volume is intended to be followed by others, in- 
cluding the Secondary and Tertiary formations. 
WILLIAM HELLIER BAILY. 
July 20th, 1875, 
