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Hamites, Baculites, &c. In these beds turtles are found, and near 
Maestricht that magnificent reptile, the Mososaurus, was discovered. 
The Cretaceous period is a marine formation, and the fossils dis- 
covered in it are chiefly of beings that lived and died in or near the 
sea. The genera of most of the shells are referable to deep-water 
species, though there are exceptions made by some geologists to the 
univalves : its duration must have been immense, and the progress 
of its deposition gradual, for we often find rolled portions and whole 
shells, on which are serpule, corals, &c., which must have attached 
themselves after the death of the shell, and lived many years before 
they were enveloped in the pulpy fluid of the chalk. I have never 
seen any older fossils than those of the Cretaceous period adhering to 
these specimens. The remains of fish are abundant in some localities, 
and generally speaking they belong to the Ctenoid and Cycloid orders 
of Agassiz*. Turtles have been discovered ; a most beautiful specimen 
from Kent is figured in the ‘Transactions of the Royal Society’ by 
Dr. Mantell. The bones of birds, resembling in their character those 
of the Albatros, have been described by Professor Owen. In the 
‘Geological Journal for 1846,’ Mr. Bowerbank has published an 
account of a large Pterodactyl found in the upper chalk of Kent. I 
have much pleasure in stating, that I am enabled, by the kindness of 
my friends, to add some new Reptilia to this formation, which have 
been ably explained by Professor Owen, adding greatly to the value 
of my work. 
A most excellent treatise on Paleontology, or natural history of 
fossil animals, has been published by F. J. Pictet of Geneva, in four 
volumes 8vo, 1844-45-46. A good general view of this work may be 
* The Ctenoid fishes have their scales on the posterior margin jagged or pectinated like a 
comb, similar to the perch. The cycloid fishes have their scales smooth on the posterior margin, 
but often ornamented with figures on the upper surface, like the salmon and herring. 
