2 
Mr. W. C. Williamson on the Recent 
Dr. Mantell supplied me with specimens from a similar accu- 
mulation at March in Cambridgeshire, equally rich in the same 
elegant organisms. On comparing these with such published 
drawings and descriptions of Lagence as were available to me, it 
was very evident that both the one and the other were exceed- 
ingly incomplete, the drawings being for the most part unre- 
cognizable caricatures, and the descriptions not comprehending 
half the forms that had come under my notice. Contemplating 
the production of a brief monograph on the subject, I wrote to 
J. Gwyn Jeffreys, Esq. of Swansea, soliciting his valuable aid, 
knowing that he possessed an excellent series of these interesting 
objects from various British localities. In reply he informed me, 
that in 1828 he had laid before the Linnsean Society a memoir on 
the same genus, which memoir the Council of the Society ordered 
to be published in their ^ Transactions.^ Mr. Jeffreys however, 
not being satisfied on some points connected with the natural hi- 
story of these animals, declined publishing the memoir until he 
had carried out further investigations, and consequently it was 
not printed. 
This memoir, embodying his views of the genus up to that 
comparatively early period, he has kindly placed in my hands, 
and also, with that generous liberality which characterizes the 
true philosopher, he has forwarded to me his entire collection of 
Lagence to be used as I thought proper. 
Under these circumstances I resolved upon a revision of the 
genus, giving figures of all the known British species, believing 
that the monograph would be neither useless nor uninteresting 
to the students of these microscopic organisms. The Boston and 
March deposits have enabled me, from their productiveness, to 
compare an immense number of specimens, and the two collec- 
tions of Mr. Jeffreys and Mr. Bean of Scarborough have afforded 
common of our Britisli species. The specimen from March, which Dr. Man- 
tell has placed in my hands, confirms my view as to the extent of this marine 
deposit. I have little doubt that it extends over the greater part of the Fen 
district, and probably it will be found to be continuous with the existing 
beaches of the coasts of Lincolnshire and Norfolk. The most curious fea- 
ture of the de])osit, as it exists at Boston and March, is the young state of 
nearly all the organisms found in it. The specimens of Rotalina Beccarii, 
Polystomella crlspa and Quinqueloculina seminidum rarely exceed the 
of an inch in diameter, which, with their highly translucent aspect, shows 
them to be in a very yomig state. The same remark applies, though in a 
less degree, to the Lageiue : does not this most strikingly illustrate the sift- 
ing power of aqueous currents, and explain the way in which such differ- 
ences have been produced in rocks, which, like the chalk, have been entirely 
formed by an accumulation of Foraminifera and other small organisms, 
which in some localities are exceedingly minute, forming very fine-grained 
strata, whilst in others they are conqmratively large, forming deposits of 
coarse texture ? 
