463 
In the upper beds, consisting of sand and gravel, and known as 
the Golden Sands of the Tagus, Mr. Smith found no organic remains ; 
but in the next inferior series of strata, composed of yellow sand, 
calcareous sandstone and blue marl, the Almada beds of Mr. Sharpe, 
marine remains abound. Of upwards of 150 species collected by 
the author, 124 have admitted of being carefully determined, and of 
these, 20 are new, 51 occur near Bordeaux, 17 in the Faluns of Tou- 
raine, 15 in the Sub-apennine and Sicilian beds, 8 in the London 
and Paris basins, and 35 are recent. Several of the species also 
occur in the tertiary deposits of Vienna, Switzerland, Turin, and 
the Morea. 
a list of five new species of Echinodermata is also given, one of 
which M. Agassiz has identified with a Molasse species. The fol- 
lowing fishes have likewise been determined by M. Agassiz :— Oxy- 
rhina Xiphodon, a Bordeaux ichthyolite; Carcharias productus, C. 
megalodon, which occurs in the London basin; Galeus aduncus, and 
Lamna denticulata; also a species of Delphinus. 
Appended to the paper is a descriptive catalogue of the new spe- 
cies by Mr. G. Sowerby, and drawings of the shells by Mr. G. 
Sowerby, jun. 
6. ‘Some remarks on the Silurian Strata between Aymestry and 
Wenlock,” by Charles Lyell, Esq., V.P.G.S. 
Two points are more particularly discussed in this paper :—Ist, 
the inferences which may be drawn respecting the dislocation of 
strata from the position of fossil corals in the bed in which they occur, 
and of the subsidences which beds containing Polyparia underwent 
during the accumulation of the upper Silurian strata; and 2ndly, 
certain features in the physical geography of the district between 
Aymestry and Wenlock, dependent on geological structure. 
1. Inferences from the position of Corals, &¢.—The corals which 
abound in the Aymestry and Wenlock limestones, in the neighbour- 
hood of Aymestry, retain, Mr. Lyell states, the position in which they 
grew, the points of attachment being inclined towards the lower part 
of each stratum, and the convex surface of the hemispherical masses 
being upwards. At Lower Lye, near Aymestry, this arrangement is 
advantageously exhibited near the junction of the Wenlock limestone 
with the lower Ludlow formation, in consequence of the layers of 
shale or mudstone marking more clearly the stratification than in 
places where the limestone is almost exclusively an aggregate of or- 
ganic remains. The Rev. T. 'T. Lewis has also noticed some rare 
instances of the roots and base of the stem of an Encrinus growing 
on the top or convex surface of a coral. ‘These facts, with the great 
size and extent of the corals, (the Catenipora escharoides sometimes 
spreading continuously in a horizontal direction for nine feet and 
even more, and a hemispherical mass of Cyathophyllum in the Lud- 
_low Museum being four feet in diameter) imply, Mr. Lyell states, 
the slow accumulation of the materials composing the upper Silurian 
strata. 
The vertical position of the corals with respect to the plane of strati- 
fication is sufficiently general to deserve particular attention, with a 
