340 Proceedings of the British Association. 
coast of Essex and Suffolk. Among the mammalia, which the au- 
thor states really belong to the crag, is the Mastodon angustidens, 
of which several teeth have recently been obtained in Norfolk from 
localities adjoining the parish of Withingham, the spot from which 
Dr. W. Smith states the specimen to have been procured which is 
figured in his ‘Strata Identified.” Mr. Charlesworth conceived 
the discovery of the remains of the mastodon in this formation, as 
affording an argument to prove the relative ages of these rocks, as 
no remains of this animal have been found in America in beds more 
ancient than the diluvial. The remaining genera of mammiferous 
animals can be identified with those now existing, or with such as 
are found in diluvial and lacustrine deposits. The author next 
notices the discovery of the mineralized remains of birds, chiefly 
bones of the extremities of natatorial tribes, a solitary instance of a 
similar discovery in America being the only one recorded. He was 
not prepared to speak concerning the different kinds of fish, but he 
stated their distribution—species of Squalus being found near Orford, 
and what Agassiz conceives to be Platex, at Cromer. Among the 
most remarkable is the Carcharias megalodon, the teeth of which 
are found in Suffolk, equal in size to specimens from the tertiary 
formations of Malta. He also alluded to the difference of the tes- 
tacea in different parts of the crag, from which he was inclined to 
infer there were several eras in its formation. No traces of the ex- 
istence of reptilia have yet been detected, which would rather sup- 
port the opinion of Dr. Beck and Deshayes, that the climate during 
the crag epoch was analogous to that of the polar regions.—Prof. 
Sedgwick stated, that he had been long aware of the existence of re- 
mains of mammalia in the Norfolk crag, although this had been dis- 
puted by Mr. Conybeare, in his work on the Geology of England 
and Wales. He was rather inclined to consider the crag as all of 
one epoch ; and Mr. Lyell had found existing species as numerous 
in the lower as in the upper crag. With regard to Mr. Charles- 
worth’s idea of the extinction of the mastodon in England before the 
formation of the diluvial beds, Prof. Sedgwick conceived that it was 
reasoning from a negative fact, and that until more extensive search 
had been made, no such inference could be fairly drawn. He also 
mentioned that remains of the beaver were found in the alluvions of 
Cambridgeshire, and that it might have existed in England a thou- 
sand years ago. He was confident that no cause still in existence 
could have produced the diluvium on the crag; its whole appeat- 
