Geological Society. 335 



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, 5 1 occur near Bordeaux, 1 7 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 mth 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 : — 1st, 

 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, S(C. — 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 inchned 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 toj) 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 Ludlow 

 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 

 view of dctennining the amount of dislocation which the enclosing 



