294 Mr. Lyell on Shells of the Genus 
rock, which have been filled from above with rubbish, con- 
sisting of angular fragments of quartzite, pieces of limestone, 
and numerous fossil shells, the whole imbedded in a calcareous 
matrix resembling that of the incumbent strata. The most 
perfect fossils, together with the greater part of the Cones, 
have been all found in this breccia filling the rents, and the 
upper parts of the breccia unite with the lowest strata of 
fossiliferous limestone in such a manner as to make it clear 
that the fissures were filled before or at the time of the depo- 
sition of the lowest strata of the limestone. The quarries in 
which these sections are exposed have been opened, not for 
the sake of the limestone but for the subjacent quartzite which 
is used for making roads, and which at some points comes up 
nearly to the surface. This quartzite, however, and the ac- 
companying transition schist, are only found at a moderate 
depth along a certain line from N.N.W. to 8.S.E., in which 
direction they form an underground ridge stretching for many 
leagues beneath the platform of limestone. At the distance 
of a few yards either east or west of this narrow ridge the 
incumbent oolite or lias is of such thickness that the quartzose 
stone cannot be worked with profit. 
Among the Ammonites which I collected myself in the rent 
or in the bed immediately covering it, or which were given 
me from this locality by M. Deslongchamps, were the follow- 
ing, which have been examined by my friend Mr. Lonsdale, 
of the Geological Society :— 
1. Ammonites Walcottii, Alum shale. Phillips, Geol. Yorkshire, p. 
164; Hunton, Geol. Trans., vol. v. part 1, p. 220; Williamson, 
ibid., p. 242; Cheltenham, Murchison, Geol. Cheltenham, p. 
tT: 
2. A. corrugatus, Inferior oolite. Dundry, M. C. tab. 451; 
Gloucester, Lonsdale, M.S. 
3. A. Stokesii, Inferior oolite? Bridport, M.C. tab. 191. Marl- 
stone, coast of Yorkshire, Williamson, Geol. Trans., vol. v. part 
1, p. 242. ; 
Among many others which were shown me at Caen and 
named by M. Deslongchamps, were Ammonites planicosta and 
A. Bucklandii, which occur in the lias in England, A. faleifer, 
found in the alum shale near Cheltenham, and 4. Strang- 
waysii and A. Murchisone, both from the inferior oolite of 
England. Associated with these I saw a Belemnite, several 
species of Plewrotomaria, fragments of a Pentacrinite and other 
fossils, which in the opinion of M. Deslongchamps indicates 
that the formation constitutes either the upper member of the 
lias, or is intermediate between the lias and the inferior oolite. 
