a6 
P. Egerton have been so kind as to render me their assistance in 
arranging and naming many of the fish, both of the Tertiary and 
Secondary formations. 
The corals of the chalk, like those of the Eocene deposits, have 
been described by W. Lonsdale. Esq., F.G.5., to whom I am much 
indebted. 
I owe to Professor Owen many obligations, particularly on this 
occasion, for his most valuable description of the chalk saurians. 
I am obliged to G. A. Coombe, Esq., of Arundel, for some beautiful 
specimens ; and to Henry Catt, Esq., of Brighton, who has a rich cabinet 
of chalk fossils, and has added within the last few years some most 
interesting specimens from the pits in the neighbourhood of Lewes. 
Mr. J. D. C. Sowerby, Mr. Dinkel, Mr. Scharf, Mr. Erxleben, and 
Mr. Lens Aldous have engraved the plates. Mr. Sowerby has also 
rendered me great assistance in my descriptions. 
In the southern, as well as some other counties of England, where 
the downs form a beautiful undulating character, the landscape is often 
broken by the appearance of white patches ; these are generally the 
remains of pits that have been opened for the purpose of procuring 
that useful substance, chalk, the material of which these hills are 
composed. Chalk is, chemically speaking, a carbonate of lime: kilns 
are built at most of the quarries for converting, by the process of 
burning, the carbonate of lime into lime, the carbonic acid being 
expelled by heat. Lime is most extensively used in building, is of 
great value in many manufactures, and is an excellent manure for 
some lands; and in these applications, to most persons begin and 
end the interest and value of the Chalk formation. To the scientific 
man, however, it opens another field of inquiry: he perceives, upon 
examination, that it often contains shells, the scales of fish, &c., mixed 
up with the white mass ; he consults the geologist, who informs him 
that the material, chalk, is only one character of an extensive forma- 
