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 hive 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 s'ecies ; 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 ruder ata 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 Paludina 
minuta. The value of the discovery of the Clacton deposit is also en¬ 
hanced by fiy ding Vertigo cylindrica and \H.) ruderata. Eut the fossils found 
at Tdacton p'oint 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, Deer. 2nd, 1843. 
I find 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. 
