﻿Geological 
  Society. 
  459 
  

  

  rock. 
  The 
  glaciated 
  surface 
  on 
  the 
  northern 
  bank 
  is 
  only 
  25 
  feet 
  

   above 
  sea-level 
  ; 
  and 
  the 
  rock-surface 
  is 
  sloping 
  down 
  at 
  a 
  precipitous 
  

   angle 
  at 
  8 
  feet 
  below 
  sea-level 
  at 
  a 
  distance 
  of 
  18 
  miles 
  from 
  the 
  

   mouth 
  of 
  the 
  river. 
  

  

  2. 
  ' 
  On 
  the 
  Clarke 
  Collection 
  of 
  Fossil 
  Plants 
  from 
  New 
  South 
  

   Wales.' 
  By 
  Edward 
  Alexander 
  Newell 
  Arber, 
  Esq., 
  B.A. 
  

  

  3. 
  ' 
  On 
  an 
  Altered 
  Siliceous 
  Sinter 
  from 
  Builth 
  (Brecknockshire)/ 
  

   By 
  Frank 
  Rutley, 
  Esq., 
  F.G.S. 
  

  

  A 
  rock-specimen, 
  given 
  to 
  the 
  author 
  many 
  years 
  ago 
  by 
  the 
  

   late 
  H. 
  W. 
  Bristow, 
  forms 
  the 
  main 
  subject 
  of 
  this 
  paper. 
  It 
  shows 
  

   no 
  trace 
  of 
  original 
  sand-grains 
  ; 
  it 
  is 
  compact, 
  and 
  with 
  a 
  fracture 
  

   platy 
  to 
  conchoidal 
  : 
  small 
  splinters 
  of 
  it 
  can 
  be 
  fused 
  on 
  their 
  

   edges 
  to 
  a 
  white, 
  frothy 
  glass. 
  Under 
  the 
  microscope 
  the 
  rock 
  is 
  

   decidedly 
  tufaceous, 
  containing 
  small 
  fragments 
  chiefly 
  of 
  pumice, 
  

   less 
  often 
  of 
  crystals 
  which 
  are 
  apparently 
  epidote. 
  In 
  the 
  slides 
  

   of 
  this 
  rock 
  and 
  in 
  some 
  of 
  the 
  siliceous 
  sinters 
  from 
  New 
  Zealand, 
  

   used 
  for 
  comparison, 
  there 
  are 
  small 
  patches 
  of 
  a 
  brown 
  substance 
  

   which 
  may 
  possibly 
  be 
  of 
  organic 
  origin 
  ; 
  in 
  connexion 
  with 
  it, 
  

   Prof. 
  Weed's 
  discovery 
  of 
  algous 
  growths 
  in 
  some 
  of 
  the 
  New 
  

   Zealand 
  sinters 
  is 
  mentioned. 
  A 
  specimen 
  of 
  hard 
  breccia, 
  also 
  

   from 
  the 
  vicinity 
  of 
  Builth, 
  is 
  described. 
  The 
  cement 
  of 
  this 
  rock 
  

   is 
  also 
  possibly 
  siliceous 
  sinter, 
  as 
  well 
  as 
  some 
  of 
  the 
  fragments, 
  

   which 
  latter 
  show 
  faint 
  evidence 
  of 
  the 
  inclusion 
  of 
  little 
  shreds 
  of 
  

   pumice. 
  

  

  November 
  20th.— 
  J. 
  J. 
  H. 
  Teall, 
  Esq., 
  M.A., 
  V.P.R.S 
  , 
  President, 
  

   in 
  the 
  Chair. 
  

   The 
  following 
  communications 
  were 
  read 
  : 
  — 
  

  

  1. 
  ' 
  Notes 
  on 
  the 
  Genus 
  Lichees? 
  By 
  Frederick 
  Hichard 
  Cowper 
  

   Reed, 
  Esq., 
  M.A., 
  F.G.S. 
  

  

  2. 
  ' 
  Some 
  Remarks 
  on 
  the 
  Meteorological 
  Conditions 
  of 
  the 
  

   Pleistocene 
  Epoch.' 
  By 
  Dr. 
  Nils 
  Ekholm, 
  Meteorologiska 
  Central- 
  

   Anstalten, 
  Stockholm. 
  

  

  The 
  opinion 
  of 
  the 
  author 
  on 
  this 
  subject 
  differs 
  in 
  some 
  im- 
  

   portant 
  respects 
  from 
  that 
  of 
  Mr. 
  Harmer. 
  He 
  considers 
  the 
  

   subject 
  under 
  two 
  heads: 
  (1) 
  What 
  are 
  the 
  meteorological 
  con- 
  

   ditions 
  necessary 
  and 
  sufficient 
  to 
  produce 
  a 
  permanent 
  ice-sheet 
  

   such 
  as 
  that 
  of 
  the 
  Great 
  Ice- 
  Age 
  ? 
  (2) 
  What 
  will 
  be 
  the 
  influence 
  

   of 
  such 
  glaciation 
  on 
  the 
  meteorological 
  conditions, 
  especially 
  on 
  the 
  

   cyclones 
  and 
  anticyclones, 
  of 
  the 
  ice-covered 
  land 
  and 
  on 
  its 
  neigh- 
  

   bourhood 
  ? 
  The 
  snow-line 
  does 
  not 
  correspond 
  with 
  the 
  mean 
  

   annual 
  isotherm 
  of 
  32°, 
  for 
  Yerchojansk 
  in 
  Siberia 
  is 
  not 
  glaciated, 
  

   whereas 
  the 
  southern 
  point 
  of 
  Greenland 
  is. 
  The 
  former 
  has 
  a 
  winter 
  

   anticyclone, 
  while 
  the 
  latter 
  is 
  traversed 
  by 
  the 
  central 
  or 
  northern 
  

   part 
  of 
  cyclones 
  during 
  the 
  whole 
  year. 
  The 
  area 
  of 
  Pleistocene 
  

   glaciation 
  in 
  America 
  and 
  Europe 
  coincides 
  with 
  the 
  areas 
  now 
  

   traversed 
  by 
  the 
  most 
  regularly-frequented 
  storm-tracks. 
  There 
  

   seems 
  to 
  have 
  been 
  about 
  the 
  same 
  difference 
  between 
  the 
  mean 
  

   annual 
  temperatures 
  of 
  Europe 
  and 
  North 
  America 
  in 
  the 
  Great 
  

  

  