128 
In the neighbourhood of Norwich the deposit forms patches of 
very variable thickness, resting upon chalk, and covered by a dense 
bed of gravel. It is best displayed at Bramerton, Whitlingham, 
Thorpe, and Postwick, and consists of sand, loam, and gravel, en- 
* closing marine, land, and freshwater shells, with ichthyolites and 
bones of mammalia; and Mr. Lyell says, it was evidently accumulated 
near the mouth of ariver. The late Mr. Woodward describes the 
chalk of Postwick as having been drilled by marine animals before 
the deposition of the crag; and the Rev. Mr. Clowes found in a per- 
foration in the chalk at Whitlingham the shell of a Pholas crispatus, 
the remainder of the perforation being filled with crag. Among 
other proofs that the strata were gradually deposited, the author 
mentioned Capt. Alexander’s discovery of an elephant’s tusk, with 
many serpule attached to it; and he infers from this fossil, that the 
remains of the mammalia were really washed into the sea of the 
Norwich crag, and were not subsequently introduced by diluvial 
action, as some observers have suspected. ‘The freshwater shells, 
although most diligently searched for, are less abundant than 
marine, and the terrestrial are still more rare; but Mr. Wigham has 
found in one bed at Thorpe, a great predominance of fluviatile tes- 
tacea. In the same pits he obtained a mastodon’s tooth at the bottom 
of the deposit, near the chalk, associated with pectens and other 
marine shells. In the beds at Postwick, he also discovered, in 
1835, part of the left side of the upper jaw of a mastodon, con- 
taining the second true molar. This fragment Mr. Owen has been 
able to identify with the Mastodon longirostris of Eppelsheim. In 
the same bed, Mr. Wigham also obtained the teeth and jaw of a 
field-mouse, larger than those of the common species; likewise 
remains of birds, and several species of fishes. ‘The horns of stags, 
bones and teeth of the horse, pig, elephant, and other quadrupeds, 
have been obtained at Postwick, Thorpe, Bramerton, &c., near 
Norwich; and this association of remains of the mastodon and 
horse, both in Norfolk and on the continents of Europe and America, 
Mr. Owen considers as a subject not without interest. 
Mr. Lyell examined also the crag north of Norwich at several 
pits between that city and Horstead, and ascertained that it was 
of the same kind, resting upon chalk, and overlaid by gravel. He 
found in it Fusus striatus, Turritella terebra, Cerithium punctatum, 
Pectunculus variabilis, Tellina obliqua, T. calcarea, Cardium edule, - 
and Cyprina vulgaris. 
3. On the third point, the relative antiquity of the Norwich to 
the Suffolk crag, and the degree of resemblance of its shells to those 
of existing series, the memoir contains much very valuable inform- 
ation. The author acknowledges his obligations for assistance 
during his researches, to Mr. J. B. Wigham, who has nearly 
doubled the number of Norwich species of testacea; to Mr. Searles 
Wood, who gave Mr. Lyell free access to his fine collection of crag 
fossils; and to Mr. G. Sowerby, for the careful comparison and de- 
termination of the recent species; he also acknowledges the aid 
afforded him by Mr. Fitch of Norwich, and Capt. Alexander of 
Southwold. 
