﻿in 
  

  

  North 
  America. 
  209 
  

  

  system, 
  as 
  he 
  defined 
  it 
  in 
  1854 
  and 
  as 
  it 
  occurred 
  in 
  his 
  typ- 
  

   ical 
  sections. 
  

  

  My 
  attention 
  was 
  first 
  attracted 
  to 
  the 
  possible 
  equivalency 
  

   of 
  the 
  Chapman 
  sandstone 
  and 
  Tilestone 
  of 
  Murchison, 
  (= 
  

   Downton 
  sandstone 
  and 
  Ledbury 
  shale), 
  by 
  noting 
  that 
  Zeptcena 
  

   lata, 
  of 
  the 
  list 
  in 
  the 
  " 
  Silurian 
  System 
  " 
  is 
  a 
  true 
  Chonetes, 
  

   and 
  closely 
  resembles 
  some 
  of 
  the 
  specimens 
  from 
  Chapman. 
  

   On 
  studying 
  up 
  the 
  definitions 
  and 
  synonymy 
  of 
  the 
  species, 
  it 
  

   became 
  evident 
  that 
  Davidson, 
  who 
  identified 
  Zeptcena 
  lata 
  

   von 
  Bach 
  with 
  Chonetes 
  striatella 
  Dalman, 
  in 
  doing 
  so, 
  was 
  

   following 
  DeKoninck. 
  In 
  quoting 
  synonymy, 
  however, 
  he 
  

   excludes 
  Sowerby's 
  fig. 
  13, 
  of 
  plate 
  5, 
  which, 
  as 
  figured, 
  pre- 
  

   sents 
  the 
  flatness 
  characteristic 
  of 
  the 
  species 
  occurring 
  in 
  the 
  

   Chapman 
  sandstone. 
  

  

  The 
  Chonetes 
  (.No. 
  M218), 
  of 
  the 
  Chapman 
  sandstone, 
  agree 
  

   with 
  Hall's 
  C 
  nova 
  scotica* 
  in 
  size 
  and 
  form, 
  and 
  from 
  descrip- 
  

   tions, 
  I 
  judge 
  that 
  the 
  small 
  specimens 
  referred 
  to 
  C. 
  canadensis 
  

   by 
  Billings, 
  f 
  having 
  the 
  proportions 
  of 
  C 
  melonica 
  are 
  identi- 
  

   cal 
  with 
  Hall's 
  species 
  C. 
  nova 
  scotica. 
  There 
  is 
  also 
  a 
  speci- 
  

   men 
  (No. 
  M250) 
  (I 
  originally 
  referred 
  it 
  to 
  Orthothetes, 
  the 
  

   hinge 
  and 
  beak 
  being 
  absent) 
  which 
  upon 
  examination 
  I 
  find 
  

   presents 
  the 
  typical 
  characters 
  of 
  Chonetes 
  Canadensis 
  Bill, 
  so 
  

   far 
  as 
  they 
  are 
  visible. 
  Dawson 
  states 
  that 
  " 
  the 
  new 
  species 
  

   Chonetes 
  nova-scotica 
  is 
  very 
  characteristic 
  of 
  the 
  upper 
  mem- 
  

   ber" 
  [of 
  the 
  Arisaig 
  section]. 
  :f 
  Hall 
  compared 
  the 
  species 
  

   with 
  " 
  C. 
  cornuta 
  of 
  the 
  Clinton 
  group 
  of 
  New 
  York,"§ 
  but 
  

   the 
  Clinton 
  species 
  is 
  much 
  smaller 
  than 
  even 
  the 
  smallest 
  

   specimens 
  in 
  the 
  Chapman 
  sandstone. 
  Billings, 
  in 
  describing 
  

   the 
  Chonetes 
  of 
  the 
  Gaspe 
  series, 
  calls 
  his 
  more 
  gibbous 
  form 
  

   Chonetes 
  melonica 
  ; 
  and 
  he 
  compares 
  this 
  with 
  C. 
  striatella 
  of 
  

   Dalman, 
  but 
  finds 
  it 
  distinct 
  (p. 
  16). 
  Chonetes 
  canadensis 
  

   Billings, 
  differs 
  from 
  the 
  description 
  of 
  C. 
  melonica 
  in 
  being 
  

   nearly 
  flat. 
  Billings 
  remarks, 
  however, 
  " 
  Small 
  specimens 
  of 
  

   this 
  species 
  [C. 
  canadensis] 
  have 
  nearly 
  the 
  proportion 
  of 
  C. 
  

   melonica, 
  hut 
  are 
  always 
  nearby 
  flat, 
  while 
  those 
  of 
  the 
  latter 
  

   are 
  always 
  more 
  convex" 
  (p. 
  18). 
  f 
  From 
  a 
  study 
  of 
  the 
  

   descriptions, 
  it 
  is 
  evident 
  that 
  these 
  "small 
  specimens," 
  referred 
  

   by 
  Billings 
  to 
  his 
  species 
  C 
  canadensis, 
  are 
  identical 
  with 
  the 
  

   form 
  described 
  by 
  Hall 
  as 
  C. 
  nova-scotica 
  — 
  thus 
  linking 
  

   together 
  the 
  Chonetes 
  of 
  the 
  transition 
  beds 
  of 
  the 
  Gaspe 
  sec- 
  

   tion, 
  formation 
  D 
  of 
  the 
  Upper 
  Arisaig 
  of 
  Nova 
  Scotia, 
  and 
  

   the 
  Chapman 
  sandstone. 
  

  

  Although 
  I 
  find 
  no 
  description 
  of 
  the 
  specimens 
  referred 
  by 
  

   Sowerbv 
  to 
  the 
  species 
  Leptmna 
  lata 
  von 
  Bach, 
  the 
  figure 
  so 
  

  

  * 
  Canadian 
  Xat. 
  and 
  Geol., 
  v, 
  144, 
  fig. 
  2. 
  f 
  Palaeozoic 
  Fossils, 
  vol. 
  ii, 
  pt, 
  i, 
  p. 
  18. 
  

   X 
  Can. 
  Nat. 
  and 
  Geol 
  , 
  v, 
  137. 
  § 
  Can. 
  Nat. 
  and 
  Geol., 
  v, 
  145. 
  

  

  Am. 
  Jour. 
  Scl— 
  Fourth 
  Series, 
  Vol 
  IX, 
  No. 
  51.— 
  March, 
  1900. 
  

   15 
  

  

  