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  PROF. 
  F. 
  SCHMIDT 
  ON 
  THE 
  SILURIAN" 
  STRATA 
  

  

  Queust., 
  Gomphoceras 
  Eichwaldi, 
  &c. 
  : 
  among 
  Gasteropoda, 
  Euompha- 
  

   lus 
  Cualteriatus, 
  Eichw., 
  Maclurea 
  helix, 
  Eichw., 
  Metoptoma 
  silurica, 
  

   Eichw., 
  Bellerophon 
  locator, 
  Eichw. 
  ; 
  among 
  Lamellibranchiata, 
  Mega- 
  

   lodon 
  unguis, 
  Eichw. 
  Both 
  classes, 
  Gasteropoda 
  and 
  Lamellibran- 
  

   chiata, 
  appear 
  here 
  for 
  the 
  first 
  time 
  with 
  us 
  ; 
  Hyolites 
  and 
  Conularia 
  

   also 
  appear 
  for 
  the 
  first 
  time 
  at 
  this 
  stage. 
  Among 
  Brachiopoda, 
  we 
  

   find 
  Orthisina 
  eoncava, 
  Pahlen, 
  0. 
  plana, 
  Pand., 
  Crania 
  antiquissima, 
  

   Eichw., 
  Siphonotreta 
  verrucosa, 
  Eichw., 
  &c. 
  The 
  other 
  classes 
  show 
  

   no 
  difference 
  from 
  those 
  of 
  the 
  preceding 
  stage. 
  Yet 
  1 
  must 
  mention 
  

   that 
  in 
  the 
  lower 
  part 
  of 
  the 
  Orthoceratite 
  Limestone 
  in 
  Esthonia 
  

   I 
  found 
  a 
  very 
  fine 
  specimen 
  of 
  Phyllograptus, 
  interesting 
  from 
  a 
  

   stratigraphical 
  point 
  of 
  view, 
  as 
  it 
  renders 
  it 
  possible 
  to 
  parallelize 
  

   our 
  Orthoceratite 
  Limestone 
  with 
  the 
  Arenig 
  of 
  England. 
  In 
  Sweden, 
  

   according 
  to 
  Tornqvist, 
  the 
  Phyllograptus-achist 
  is 
  intercalated 
  

   in 
  the 
  Orthoceras-hmestone 
  ; 
  and 
  the 
  same 
  author 
  has 
  already 
  

   pointed 
  out 
  the 
  similarity 
  of 
  the 
  above-mentioned 
  Phyllograptus- 
  

   schists 
  and 
  the 
  British 
  Arenig. 
  

  

  Stage 
  C. 
  C 
  1, 
  Echinosphcerite 
  Limestone 
  Sfc. 
  

  

  The 
  third 
  principal 
  stage, 
  C, 
  of 
  our 
  Lower 
  Silurian 
  may 
  also 
  be 
  

   subdivided 
  into 
  three 
  smaller 
  stages. 
  The 
  first, 
  C 
  1, 
  is 
  the 
  widely 
  

   spread 
  Echinosphcerites-hmeBtone. 
  AVe 
  may 
  follow 
  it 
  from 
  the 
  Wol- 
  

   chow 
  throughout 
  our 
  whole 
  Silurian 
  country 
  as 
  far 
  as 
  the 
  island 
  

   of 
  Odensholm, 
  and 
  thence 
  all 
  over 
  Scandinavia. 
  Its 
  thickness 
  may 
  be 
  

   from 
  20 
  to 
  50 
  feet. 
  By 
  far 
  the 
  most 
  characteristic 
  fossils 
  are 
  Echino- 
  

   .sjili" 
  ,-iii 
  s 
  <mr(intium, 
  Gyll.. 
  and 
  Orthoceras 
  regulare, 
  Schloth., 
  the 
  

   former 
  predominating 
  in 
  the 
  upper 
  part 
  of 
  our 
  stage, 
  the 
  latter 
  in 
  the 
  

   lower, 
  although 
  it 
  certainly 
  is 
  not 
  possible 
  to 
  trace 
  all 
  over 
  the 
  country 
  

   two 
  subdivisions 
  individualized 
  by 
  the 
  above-named 
  fossils. 
  Our 
  stage 
  

   C 
  1 
  is 
  the 
  richest 
  in 
  Trilobites, 
  and 
  is 
  also 
  very 
  rich 
  in 
  many 
  other 
  

   classes 
  : 
  yet 
  our 
  knowledge 
  of 
  the 
  fauna 
  is 
  by 
  no 
  means 
  complete, 
  and 
  

   every 
  year 
  some 
  new 
  species 
  may 
  be 
  discovered. 
  The 
  character 
  of 
  the 
  

   fauna 
  is 
  not 
  at 
  all 
  uniform 
  ; 
  and 
  many 
  local 
  faunas 
  might 
  be 
  distin- 
  

   guished. 
  Among 
  Trilobites 
  we 
  find 
  Phacops 
  (Pterygometopus) 
  Pan- 
  

   deri, 
  mihi, 
  the 
  first 
  species 
  of 
  the 
  subgenus 
  Chasmops, 
  namely 
  P. 
  (C.) 
  

   nasuta, 
  mihi, 
  jrrcecurrens, 
  mihi, 
  and 
  Odini, 
  Eichw., 
  Cheirurus 
  eocsid, 
  

   Beyr., 
  the 
  subgenus 
  Nieszlcoivslia 
  with 
  Cheirurus 
  variolaris, 
  Linnars., 
  

   and 
  Cheirurus 
  globus. 
  Ang., 
  Illcenus 
  Sclimidti, 
  Mesz., 
  tauricomis, 
  Kut., 
  

   JJahnanni, 
  Volb., 
  Asaphus 
  Weissii, 
  Eichw., 
  Kowaleivshii, 
  Lawr., 
  

   devexus, 
  Eichw., 
  delpliinus, 
  Lawr., 
  tectieaudatus, 
  Steinh., 
  Lichas 
  tri- 
  

   cuspidata, 
  Beyr., 
  and 
  others; 
  among 
  Cephalopoda, 
  Lituites 
  perfectus, 
  

   Wahlenb., 
  (Orth.undulatus, 
  Queust.), 
  teres, 
  Eichw. 
  (both 
  in 
  the 
  lower 
  

   stage), 
  Pa 
  la>onautilus 
  Odini, 
  Eichw., 
  Rom., 
  Orthoceras 
  regular 
  e, 
  Sch]., 
  

   vertebrale, 
  Eichw., 
  Cyrtoceras 
  Odini, 
  Eichw. 
  ; 
  among 
  Gasteropoda, 
  

   Pleurotomana 
  elliptica, 
  His., 
  Ecculiomplmlus 
  alatus, 
  Bom., 
  Subidites 
  

   prisons, 
  Eichw., 
  Bellerophon 
  megalostoma, 
  and 
  many 
  others; 
  among 
  

   Acephala 
  a 
  good 
  many 
  forms 
  of 
  Modiolopsis, 
  and 
  allied 
  genera 
  not 
  

   yet 
  well 
  determined 
  ; 
  among 
  Brachiopoda, 
  Orthisina 
  ascendent, 
  

   Pand., 
  0. 
  hemipronites, 
  Buch, 
  0. 
  squamata, 
  Pahlen, 
  0. 
  pyrum, 
  

  

  

  