PREFACH. 
In the year 1846 Mr. G. B. Sowerby proposed to publish at intervals a series of Plates 
illustrative of the Crag and Jiondon Clay Fossils, to which Mr. Edwards and myself had 
undertaken to supply the descriptions. It was contemplated to issue alternately a 
number of each formation in furtherance of this object. ‘The first of these serials was to 
be upon the Crag; and at the meeting of the British Association, held in September, 1846, 
at Southampton, a specimen plate of the Crag Fossils was exhibited. In January, 
1847, Dr. Bowerbank conceived the idea of establishing a society for the purpose of 
figuring and describing the fossils of Great Britain, in which he was supported by Dr. 
Fitton, the late Dr. Buckland, and other influential Geologists. There was then in existence 
a private association, called the London Clay Club, which was composed of a limited 
number of Tertiary Geologists, who assembled periodically at each other's houses for the 
study of Eocene Geology, and this was looked upon by the promoters of the contemplated 
new society as a good promise of material for its support. The desire of encouraging 
such an object rapidly extended, and a large number of gentlemen speedily enrolled 
themselves as members of the new society. ‘lhe Crag Formation had been well examined 
by myself, and as it appeared to be one that was best known, seemed to offer to the 
friends of the undertaking the most fitting opportunity for commencement; and as | 
was particularly desirous of having the Crag fossils figured and described, I conceived 
this a more certain mode of extending the knowledge of the contents of that formation 
than the one I had previously entered into, and made arrangements accordingly with 
Mr. Sowerby for the alteration, and set to work immediately upon the portion allotted 
to my labours. My friend, Mr. Edwards, as before stated, intended to publish parts 
alternately with myself; but the older Tertiary Formations being much richer in species, 
his portion of the work was not so readily prepared as that of the Crag; moreover, what 
at that time appeared a feasible mode of proceeding has, by the course of events, become 
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