The original Nature and subsequent Alteration of Mica-schist. 157 



had afforded no vestiges of life, and that the transitional groups 

 of strata uniting two great systems had not afforded in any country 

 a link connecting one class of animals with another. 



2. " Notice of a Section at Moktree." By R. Lightbody, Esq. 



The lower portion of this section was stated to exhibit the 

 Aymestry limestone with its characteristic honeycomb structure, and 

 showing at its upper limit a basin-shaped depression containing 

 beds of sandy clay deposited parallel to its sides, and unconformable 

 to the Aymestry limestone, though at a little distance from the 

 trough this unconformity disappears. These argillaceous beds con- 

 tain Lower Ludlow fossils, though they overlie the Aymestry lime- 

 stone ; the author consequently proposes that the latter term should 

 no longer be used as a separate subdivision. He also remarked that, 

 in consequence of a fault bringing the Upper and Lower Ludlow 

 beds against one another, without having altered their dip, many 

 fossils have been stated to occur in the Upper Ludlow which really 

 belong to the Lower. 



May 6. — Leonard Horner, Esq., Vice-President, in the Chair. 



The following communications were read : — 



1. " On the Brick-pit at Lexden, near Colchester." By the Rev. 

 Osmond Fisher, M.A., F.G.S.; with a Note on the Coleoptera, by 

 T. V. Wollaston, Esq., F.L.S. 



Lexden is a village about a mile west of Colchester, and is situated 

 on a plateau on the south side of the Valley of the Colne. The 

 brick pit shows this tableland to consist of thick beds of gravel and 

 sand, resting upon the London Clay, and containing at its southern 

 extremity a talus of old gravel. This stratified gravel is overlain 

 by brick- earth and soil, and is believed by the author to be that 

 which elsewhere underlies the Boulder-clay ; and he states that be- 

 tween it and the brick-earth there is, in one locality, a layer of peat 

 containing bones of Elephas primigenius, and the remains of many 

 insects ; the latter are considered by Mr. Wollaston to differ from 

 British recent species, and to indicate a warmer climate than now 

 obtains in the district. 



2. " On the original nature and subsequent alteration of Mica- 

 schist." By H. C. Sorby, Esq., F.R.S., F.G.S. 



When ripples are formed whilst material is being deposited, 

 there is a structure generated which the author has, in former 

 papers, termed "ripple-drift," and which he now described. This 

 structure he stated might frequently be seen in polished sections of 

 clay-slates, and also, in a form modified through metamorphism, in 

 many mica-schists. From a consideration of the facts revealed by 

 an examination of those rocks, he concluded that mica-schist is of se- 

 dimentary origin, metamorphosed after deposition, and sometimes after 

 the production of cleavage and other physical changes, and that the 

 bands of different minerals represent the planes of original deposition. 



3. " On the Fossil Corals of the West Indies."— Part I. By 

 P. Martin Duncan, M.B.Lond., F.G.S. 



The aucity of information concerning the Geology and Palseon- 



