104 Lanhester — Crag. 
still living. This so-called ‘Coralline Crag’* lies on London Clay, 
and is seldom more than 20 feet in thickness. The ‘ Red Crag,’ so 
called from its iron-stained appearance, is an irregularly stratified 
deposit, composed of rather coarse sand and fragments of shells, 
abounding also in more perfect remains, but very rarely affording 
the valves of Conchifera, opposed or én situ. It extends over a 
larger area than the Coralline Crag, abont 200 square miles, part 
of which is in Essex. The Red Crag, rarely exceeding 20 feet in 
thickness, in most localities rests on the London Clay, the Lower 
Crag having probably been denuded: itis occasionally, however, 
found resting on the latter. At the base of both Crags, when rest- 
ing on the London Clay, a deposit of rounded concretionary nodules, 
derived from and containing the fossils of the London Clay, is 
found, and is worked for the nodules, which in great part consist of 
phosphate of lime, and are manufactured into manure. Associated 
with these nodules, are teeth of Mastodon, Rhinoceros, and other 
Mammals,} which have been derived perhaps from earlier Pliocene, 
perhaps from Miocene strata, and are similar, in some respects, to 
those obtained at Eppelsheim in Germany. In addition to these, 
there are the remains of large Cetacea, much worn and rolled, 
as well as the teeth of the large Carcharodon and Oxyrhina. 
These are probably the remains of a former Pliocene deposit, 
broken up like the Miocene beds at the beginning of the Crag era. 
Similar vertebrate fossils and phosphatic nodules are also dispersed 
at intervals in the higher strata of the Red Crag. Their occurrence 
here has led to much confusion, since they have been, and still are 
by many, regarded as indigenous to the Crag. 
From the Red Crag 231 species of Mollusca have been obtained, 
of which 189 belong also to the Coralline Crag; and 92 are found 
only in the Red Crag. Of the latter group, 42 are extinct, and 50 
are still living. 
With the Mammaliferous or Norwich Crag, Ido not purpose to 
deal in this paper, as it is a much later deposit. 
The Coralline and Red Crags occupy the south-east sea-board of 
Suffolk and a part of Essex; extending along the coast about twenty 
miles, and inland twelve miles more or less. 
The Antwerp Crags.—If the German Ocean be crossed from 
Orford on the Suffolk coast in a direction almost due south-east, the 
mouth of the River Escaut will be reached, on which stands the 
* Of the three recognized divisions of the ‘ English Crag,’ the lowest has been 
known as the ‘Coralline Crag’ ever since Mr. Charlesworth so named it in 1835, on 
account of its abounding with little coral-like fossils, which, however, when duly 
studied, were found to be Bryozoa (Polyzoa); Corals being exceedingly rare in it. 
‘Bryozoan Crag’ ought, therefore, to take the place of this common misnomer; 
but ‘ White Crag,’ or ‘ Lowest Suffolk Crag,’ are better names for this division, and 
already in use.—Epir. Gzor. Mac. 
} It appears from the researches of Dr. Falconer, that these fossils are identical 
with Sub-Apennine forms: others, however, consider them of Miocene age. 
Whichever is the correct view, there is no doubt that the fossils are extraneous, and 
derived from earlier beds. 
