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MR.  E.  WETHERED  ON  THE  MICROSCOPIC  [May  1 893, 
19.  On  the  Microscopic  Structure  of  the  Wen  lock  Limestone,  with 
Remarks  on  the  Eormation  generally.  By  Edw.  Wethered, 
Esq.,  E.G.S.,  E.C.S.,  E.R.M.S.  (Read  February  22nd,  1893.) 
[Plate  VI.] 
Contents. 
I.  Introduction  . 
II.  May  Hill  Series  of  the  Wenlock  Limestone  . 
III.  Wenlock  Limestone  at  Piirley,  near  West  Malvern 
IV.  Wenlock  Limestone  at  Ledbury  . . 
V.  General  Summary  . 
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I.  Introduction. 
The  general  features  and  fossils  of  the  Wenlock  Limestone  have  been 
described  by  several  geologists,  but  I  am  not  aware  of  any  endea¬ 
vour  to  make  a  systematic  examination  of  the  microscopic  structure. 
The  value  of  such  work  has  been  greatly  underestimated  ;  for  inves¬ 
tigations  which  I  have  made  show  that,  although  much  information 
as'  to  the  formation  and  structure  of  the  rock  may  be  gained  by 
observations  made  without  the  assistance  of  a  microscope,  yet  the  use 
of  this  instrument  brings  into  view  important  facts  which  are 
not  perceived  by  the  unassisted  eye. 
In  this  paper  I  do  not  attempt  an  exhaustive  enquiry ;  to  do  this 
it  would  be  necessary  to  make  several  visits  to  the  localities  from 
which  specimens  for  examination  were  collected,  and  this  I  have 
been  able  to  accomplish  onty  in  the  case  of  the  Wenlock  Limestones 
exposed  within  a  convenient  distance  from  Cheltenham.  I  have 
therefore  selected  what  I  regard  as  typical  sections  of  the  limestone 
in  the  neighbourhood  of  May  Hill  in  Gloucestershire,  and  in  the 
adjoining  portion  of  the  county  of  Hereford. 
The  procedure  has  been  to  take  samples  from  several  beds. in 
each  exposure  of  the  rock,  and  to  grind  down  the  usual  thin  sections 
for  examination  under  a  microscope.  These  I  prepare  myself,  and 
I  mention  the  fact  because  it  seems  to  me  important  for  this 
reason :  very  many  slides  require  to  be  made  for  a  paper  like  the 
present  one,  and  each  must  be  adjusted,  with  regard  to  actual 
thinness,  according  to  the  structure  which  occurs.  This  can  be 
determined  only  by  a  person  conversant  with  the  organisms,  the 
calcareous  remains  of  which  have  built  up  the  limestone. 
1  may  Hiention  that  to  bring  out  obscure  structure  in  slides  it  is 
important  to  give  a  final  polish  to  the  section  before  removing  it 
to  a  permanent  glass  slide.  This  is  best  done  b}^  rubbing,  on  a 
moist  thick  flannel  sprinkled  with  putty  powder.  In  this  way 
structure  is  developed  which  would  otherwise  be  lost. 
