﻿OP 
  THE 
  BALTIC 
  PKOVLNCES 
  OP 
  KT7SSIA. 
  523 
  

  

  stage 
  E 
  consists 
  of 
  hard 
  yellowish 
  limestone, 
  intercalated 
  with 
  

   marls, 
  and 
  is 
  of 
  a 
  lesser 
  thickness 
  than 
  the 
  foregoing 
  stage, 
  never 
  

   more 
  than 
  abont 
  30 
  feet. 
  The 
  fauna 
  is 
  intermediate 
  between 
  the 
  

   stages 
  D 
  and 
  F, 
  and 
  shows 
  clearly 
  some 
  relations 
  to 
  the 
  English 
  

   Caradoc 
  and 
  the 
  American 
  Trenton 
  groups. 
  In 
  the 
  frequent 
  occur- 
  

   rence 
  of 
  L&ptcena 
  sericea, 
  Sow., 
  and 
  Strophomena 
  deltoidea, 
  Conr., 
  

   some 
  corals, 
  as 
  Favosites, 
  sp., 
  and 
  Streptelasma, 
  sp., 
  and 
  Gasteropoda, 
  

   such 
  as 
  Murchisonia 
  insignis, 
  Eichw., 
  it 
  shows 
  near 
  relations 
  to 
  the 
  

   stage 
  F; 
  while 
  other 
  forms, 
  such 
  as 
  Qyclocrinus 
  SpassJcii, 
  Eichw., 
  and 
  

   Orthis 
  testudinaria 
  connect 
  our 
  stage 
  with 
  the 
  foregoing 
  stage 
  D. 
  

   In 
  the 
  same 
  way 
  the 
  upper 
  part 
  of 
  the 
  Jewe 
  stage 
  (the 
  Kegel 
  stage) 
  

   shows 
  relations 
  both 
  to 
  the 
  lower 
  part 
  of 
  the 
  Jewe 
  stage 
  and 
  to 
  

   the 
  Wesenberg 
  stage 
  (E), 
  and 
  serves 
  to 
  prove 
  that, 
  as 
  I 
  said 
  before, 
  

   there 
  has 
  not 
  been 
  any 
  distinct 
  interruption 
  or 
  break 
  in 
  the 
  evo- 
  

   lution 
  of 
  animal 
  life 
  during 
  the 
  formation 
  of 
  our 
  Lower 
  Silurian 
  or 
  

   Ordovician 
  sytem. 
  The 
  characteristic 
  Trilobites 
  of 
  the 
  Wesenberg 
  

   zone 
  are 
  Phacops 
  Nieszkowskii, 
  mihi, 
  P. 
  (Ohas?noj>s) 
  wesenbergensis, 
  

   mihi, 
  Encrinurus 
  Seebachi, 
  mihi, 
  Cybele 
  brevicauda, 
  Aug., 
  Lichas 
  

   Fichwaldi, 
  Nieszk.., 
  Isotelus, 
  sp., 
  some 
  of 
  them 
  passing 
  over 
  also 
  to 
  

   the 
  lower 
  strata 
  of 
  the 
  stage 
  E. 
  

  

  In 
  Scandinavia 
  our 
  stage 
  E 
  is 
  not 
  clearly 
  represented. 
  In 
  that 
  

   region, 
  as 
  during 
  the 
  formation 
  of 
  the 
  Jewe 
  stage, 
  slaty 
  rocks 
  with 
  

   Trinucleus- 
  and 
  Graptolite-schists 
  were 
  deposited. 
  I 
  have 
  already 
  

   pointed 
  out 
  that 
  the 
  general 
  character 
  of 
  the 
  fauna 
  of 
  our 
  Wesenberg 
  

   zone 
  allows 
  us 
  to 
  compare 
  our 
  strata 
  with 
  those 
  of 
  the 
  Caradoc 
  or 
  

   Bala 
  group 
  of 
  England 
  and 
  the 
  Trenton 
  of 
  North 
  America. 
  

  

  Stage 
  E. 
  Lyckholm 
  and 
  Borhholm 
  Zones. 
  

  

  Stage 
  E 
  (the 
  uppermost 
  of 
  our 
  Lower 
  Silurian) 
  is 
  very 
  rich 
  

   in 
  fossils, 
  and 
  very 
  important 
  also 
  as 
  affording 
  means 
  of 
  correlating 
  

   our 
  rocks 
  with 
  foreign 
  Silurian 
  strata. 
  With 
  ns 
  it 
  is 
  restricted 
  

   to 
  Esthonia, 
  and 
  begins 
  in 
  the 
  east 
  near 
  the 
  Peipus 
  Lake. 
  It 
  can 
  

   be 
  traced 
  westward 
  not 
  only 
  over 
  the 
  whole 
  of 
  the 
  mainland 
  of 
  

   Esthonia, 
  but 
  also 
  over 
  the 
  peninsula 
  of 
  Nucko, 
  and 
  the 
  island 
  of 
  

   Worms 
  and 
  the 
  northern 
  part 
  of 
  Dago. 
  I 
  formerly 
  separated 
  this 
  

   stage 
  into 
  two 
  zones, 
  the 
  Lyckholm 
  zone 
  (2 
  a) 
  and 
  the 
  Borkholm 
  

   zone 
  (3). 
  They 
  are, 
  however, 
  so 
  nearly 
  allied 
  in 
  their 
  faunas 
  that 
  I 
  

   cannot 
  separate 
  them 
  at 
  present 
  as 
  distinct 
  stages, 
  but 
  regard 
  them 
  

   rather 
  as 
  representing 
  two 
  subdivisions, 
  the 
  Lyckholm 
  zone 
  (F 
  1), 
  

   and 
  the 
  Borkholm 
  zone 
  (F 
  2). 
  The 
  former 
  consists 
  of 
  grey 
  and 
  yellow 
  

   limestones 
  and 
  marls 
  (often 
  dolomitic) 
  ; 
  the 
  latter 
  of 
  hard 
  white 
  coral- 
  

   limestone. 
  Both 
  stages 
  together 
  may 
  attain 
  a 
  thickness 
  of 
  100 
  feet. 
  

   The 
  fauna 
  of 
  both 
  subdivisions 
  is 
  very 
  rich, 
  the 
  richest 
  of 
  all 
  our 
  

   Silurian 
  stages, 
  just 
  as 
  in 
  the 
  corresponding 
  middle 
  Bala 
  group 
  

   (Sedgwick) 
  of 
  Britain. 
  The 
  corals 
  appearing 
  in 
  the 
  foregoing 
  stage 
  

   are 
  richly 
  developed 
  ; 
  most 
  of 
  the 
  Upper 
  Silurian 
  genera 
  are 
  repre- 
  

   sented 
  already 
  ; 
  but 
  the 
  species 
  are 
  for 
  the 
  greater 
  part 
  different. 
  The 
  

   other 
  classes 
  are 
  also 
  very 
  rich 
  in 
  species, 
  namely 
  the 
  Gasteropoda, 
  

   Cephalopoda, 
  Acephala, 
  Brachiopoda, 
  and 
  Bryozoa. 
  There 
  are 
  also 
  a 
  

  

  2n2 
  

  

  