﻿OF 
  THE 
  BALTIC 
  PROVINCES 
  OF 
  RUSSIA. 
  527 
  

  

  In 
  Sweden 
  our 
  stages 
  G 
  and 
  H 
  are 
  distinctly 
  represented 
  on 
  the 
  

   island 
  of 
  Gothland 
  — 
  the 
  Wisby 
  group, 
  determined 
  by 
  Lindstrom 
  and 
  

   myself, 
  representing 
  our 
  stage 
  G, 
  and 
  the 
  lower 
  part 
  of 
  the 
  Middle 
  

   Gothland, 
  characterized 
  by 
  Pentamerus 
  esthonus 
  and 
  the 
  typical 
  Le- 
  

   per 
  ditia 
  baltica, 
  His., 
  our 
  stage 
  H. 
  In 
  Norway 
  I 
  found 
  both 
  our 
  

   stages 
  on 
  the 
  island 
  of 
  Malmo, 
  in 
  the 
  Bay 
  of 
  Christiania. 
  On 
  the 
  

   eastern 
  side 
  of 
  that 
  island 
  (still 
  regarded 
  by 
  Kjerulf 
  as 
  belonging 
  to 
  

   the 
  Lower 
  Silurian, 
  stage 
  5 
  b) 
  I 
  collected 
  Leperditia 
  Hisingeri, 
  Pha- 
  

   cops 
  elegans, 
  Strophomena 
  pecten 
  ; 
  on 
  the 
  western 
  side 
  I 
  met 
  with 
  

   Kjerulf 
  s 
  stage 
  6, 
  with 
  Pentamerus 
  esthonus 
  audi 
  Leperditia 
  baltica, 
  as 
  

   in 
  the 
  Middle 
  Gothland. 
  The 
  comparison 
  of 
  both 
  our 
  stages 
  G 
  and 
  

   H 
  with 
  British 
  ones 
  is 
  rather 
  difficult. 
  In 
  Britain 
  the 
  May-Hill 
  

   Sandstone 
  and 
  Woolhope 
  Limestone, 
  with 
  the 
  Wenlock 
  Shale, 
  may 
  

   be 
  regarded 
  as 
  corresponding 
  deposits. 
  But 
  the 
  typical 
  English 
  

   Pentamerus 
  oblongus, 
  Sow., 
  seems 
  to 
  be 
  different 
  from 
  our 
  and 
  the 
  

   Scandinavian 
  species, 
  both 
  in 
  a 
  zoological 
  and 
  stratigraphical 
  point 
  

   of 
  view, 
  although 
  Mr. 
  Davidson 
  has 
  united 
  our 
  P. 
  esthonus 
  with 
  P. 
  

   oblongus. 
  The 
  former 
  is 
  much 
  larger 
  and 
  always 
  trilobed 
  in 
  front 
  : 
  

   it 
  occurs 
  with 
  us 
  and 
  in 
  Scandinavia 
  in 
  a 
  geological 
  horizon 
  nearly 
  

   allied 
  to 
  the 
  English 
  Wenlock 
  Limestone 
  ; 
  while 
  P. 
  oblongus, 
  in 
  

   England, 
  belongs 
  to 
  the 
  very 
  bottom 
  of 
  the 
  Upper 
  Silurian, 
  the 
  

   May-Hill 
  or 
  Upper 
  Llandovery 
  group. 
  On 
  the 
  other 
  hand 
  the 
  large 
  

   Pentamerus 
  described 
  and 
  figured 
  by 
  Prof. 
  J. 
  Hall, 
  from 
  the 
  Clinton 
  

   group 
  of 
  America, 
  as 
  P. 
  oblongus, 
  seems 
  to 
  be 
  very 
  nearly 
  the 
  same 
  as 
  

   our 
  P. 
  esthonus 
  ; 
  and 
  so 
  the 
  general 
  correlation 
  of 
  our 
  stages 
  G 
  and 
  H 
  

   with 
  the 
  American 
  Clinton 
  group 
  would 
  present 
  no 
  difficulties, 
  as 
  

   even 
  the 
  other 
  fossils 
  seem 
  partly 
  to 
  be 
  identical. 
  

  

  While 
  in 
  England 
  we 
  cannot 
  observe 
  any 
  stages 
  strictly 
  corre- 
  

   sponding 
  to 
  our 
  zones 
  G 
  and 
  H, 
  yet 
  in 
  the 
  far 
  north, 
  in 
  the 
  Petschora 
  

   country, 
  and 
  in 
  Eastern 
  Siberia, 
  we 
  find 
  exactly 
  corresponding 
  repre- 
  

   sentatives 
  of 
  the 
  above-mentioned 
  stages. 
  InEastern 
  Siberia, 
  between 
  

   the 
  rivers 
  Wilni 
  (affluent 
  of 
  the 
  Lena) 
  and 
  Olenek, 
  there 
  are 
  Upper 
  

   Silurian 
  limestones, 
  recognized 
  by 
  Meak 
  and 
  Czekanowski, 
  with 
  Caly- 
  

   mene 
  Blumenbachii, 
  Phacops 
  elegans, 
  Strophomena 
  pecten, 
  Leptocoelia 
  

   Duboisi 
  ?, 
  and 
  the 
  new 
  Leperditia 
  ivilniensis, 
  exactly 
  the 
  same 
  as 
  the 
  

   limestones 
  of 
  our 
  Jorden 
  stage 
  (G 
  1) 
  ; 
  while 
  on 
  the 
  lower 
  Tunguska 
  

   river, 
  near 
  Turnschausk, 
  Czekanowski 
  found 
  coral-limestones 
  with 
  a 
  

   Pentamerus 
  very 
  nearly 
  representing 
  our 
  P. 
  esthonus. 
  In 
  1846, 
  

   Count 
  Keyserling 
  had 
  already 
  described 
  Silurian 
  limestones 
  on 
  

   the 
  Waschkina 
  river, 
  on 
  the 
  Arctic 
  Ocean 
  (near 
  the 
  mouth 
  of 
  the 
  

   Petschora 
  river, 
  west 
  of 
  the 
  Ural 
  Mountains), 
  with 
  Pentamerus 
  

   samojedicus 
  (nearly 
  allied 
  to 
  P. 
  esthonus), 
  typical 
  Leperditia 
  marginata, 
  

   and 
  common 
  Upper 
  Silurian 
  corals, 
  which 
  also 
  may 
  be 
  regarded 
  as 
  

   representing 
  our 
  stage 
  H, 
  or 
  Kjerulf 
  's 
  stage 
  6. 
  

  

  Stage 
  I, 
  or 
  Lower 
  Oesel 
  Zone. 
  

  

  The 
  stage 
  I 
  (formerly 
  7) 
  occupies 
  the 
  south-west 
  corner 
  of 
  our 
  

   Silurian 
  territory 
  on 
  the 
  mainland 
  of 
  Esthonia, 
  and 
  a 
  narrow 
  space 
  

   along 
  the 
  cliff 
  on 
  the 
  north 
  coast 
  of 
  the 
  islands 
  Mohn 
  and 
  Oesel. 
  

  

  