LETTERS FROM JOHN BROWN TO S. P. WOODWARD. 139
affords a better opportunity for collecting a suite of British land shells
than the locality in question, and especially the more rare species. You,
Sir, have determined 36 species, and three more species have been added
since, viz.:— Helix ruderata (Studer), Vertigo angustior, and Bulimus
obscurus. In all, 39 species.
The Freshwater species found up to the present time are nine in number,
making in all 48 species; and these can be collected with such facility,
the individuals of each species being so numerous as to sufficiently reward
anyone who wishes to possess the small and rarer British land shells.
It is an excellent suggestion of yours to boil the peat. It is true I have
collected them all without this aid, but many of the helices are broken at
the mouth, by, doubtless, so much washing and stirring about in cold
water, which I have no doubt boiling in my large brewing copper would
have obviated. Some of the peat is hard and compact, so much so that
thousands of these fossils are broken in trying to disengage them from the
matrix; and, as was before observed, the shells being sufficiently numerous
to reward the process, boiling is certainly a remedy, and which I shall put
in practice in my future searches.
Twelve species of Helix have already been found, and there appears
to be many more of the genus, but they are at present undetermined.
The two deposits at Clacton and Copford are the only localities, if I
mistake not, where Helix ruderata has been found as a fossil, and as a
recent species in England [it] is, I believe, unknown, although it probably
may yet be found as a native of England, seeing that it has been met
with among the fossils of two distinct Freshwater deposits that are divided
by a space [of] 20 miles. The Clacton deposit has yielded the greater
number of specimens of ruderata.
There is a stratum of red sand in the cliff at the latter place, about
three feet above high water mark, where Helix ruderata is more frequently
found; while in the Copford Post Tertiary beds only one specimen has
been found at present, after diligent search. But this paucity of ruderata
in the Copford Post Tertiary beds is amply made up by the abundance
of Helix lamellata, H. aculeata, H. fulva, H. pygmea [sic], H. radiatulus,
[sic] Vertigo angustior, Pupa anglica, etc., etc.
Both the Freshwater deposits of Clacton and Copford have features
peculiar to each. The Copford deposit is abundant in shells that in other
localities are rarely met with, though probably none of them are extinct ;
while that at Clacton possesses species that are extinct in England,'but
now found living in France—viz., the Littorina, Unio, and Paludiua
minuta. The value of the discovery of the Clacton deposit is also en-
hanced by finding Vertigo cylindrica and [H.] ruderata. Put the fossils found
at Clacton point to a much higher antiquity than those from the Post
Tertiary beds at Copford, but the deposit below the Post Tertiary strata
at the latter place appears by its mammalian fossils to be contemporaneous
with that at Clacton.
It is very delightful to trace the relative ages of these deposits and
determine them by their organic remains. Peace, rest and happiness
to the manes of the late Dr. Wm. Smith, for the key which he had the
honour of find into gunlock the mysteries which belong to these pursuits !
Stanway, Decr. 2nd, 1843.
I rind your friend Mr. Harris a very valuable correspondent. I have
received from him some valuable specimens both of Green sand and
Chalk fossils, Gault . . . Teeth and Palates of fish.
You mentioned Valvata antiqua in your last letter. If I mistake not
Mr. S. Wood has found that species at Clacton, for he has searched those
beds much more than I have, who live within 17 miles of them.