304 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 9, 
silicification not so great as might at first sight appear ; for in Antigua 
and elsewhere vegetable forms had been converted into flint as com- 
pletely and distinctly. 
Mr. Woopwarp cited the hot springs in the Island of St. Michael 
as converting portions of vegetables still growing into flint. He had 
heard of the ends of piles being converted into flint in the course of 
thirty years, but had not yet seen them. 
Mr. Jenxrys inquired whether the Osmundacez from different for- 
mations offered any evidence of the climate under which they lived. 
He thought that where vegetable structures were perfectly preserved 
in flint, the process of silicification had gone on but slowly ; but this 
fell more within the province of the chemist than the geologist. 
Mr. Hurxe suggested the possibility of the fern having contained 
a certain amount of silica while still living. 
Prof. Morris referred the fossil to the Thanet Sands. He thought 
that the silica in fossilized coniferous and endogenous wood varied in 
character, and this might throw some light on the process of conver- 
sion. He considered that objects containing phosphate of lime, and 
those containing carbonate of lime, were subject to different processes 
of silicification. 
Mr. Wuiraker was strongly of opinion that the fossil had been 
derived from quite the upper part of the Thanet Sands. 
Prof. Duncan called attention to the process of silicifiation as ex- 
hibited by the Antiguan corals, in which one highly insoluble mineral 
had been replaced by another almost as insoluble. 
Mr. Carrutuers, in reply, did not think that any thing could be 
predicated as to climate from extinct species ; if this were attempted, 
a similar error to that with regard to the climate under which the 
fossil Elephants were supposed to have lived, might be repeated. 
Existing Osmundacez contained no silica in their structure. The 
peculiarity of the fossil under consideration was the preservation of 
the contents of the cells, even to the starch, which is so readily de- 
composed. The difficulty of accounting for the replacement of soft 
vegetable matter by hard mineral silica, seemed to him great. 
2. The Oorrres of NorrHampronsHiReE. By Samvuet Suarp, Esq., 
PE Seabee Gas 
INTRODUCTION. | 
Ir is not without misgiving that I venture to offer to the notice 
of the Geological Society the following Memoir—justified in its 
production only by the fact that, during a residence of some years 
in Northamptonshire, I have been enabled, in the intervals of much 
other occupation, to acquire some familiarity with the geology of 
my own neighbourhood, and to make a collection of local fossils, 
which, in deference to “ the inexorable logic of facts,” I cannot but 
anticipate will prove of greater importance, as illustrative of the 
geoloay of the district, than any paper of which I may be the 
author. 
