﻿162 
  T. 
  DAVIDSON 
  AND 
  W. 
  KING 
  ON 
  THE 
  TEHSIEBELLIDiB. 
  

  

  some 
  of 
  the 
  English 
  specimens 
  : 
  it 
  is 
  also 
  well 
  shown 
  in 
  a 
  cast 
  w© 
  

   have 
  been 
  favoured 
  with 
  by 
  Dr. 
  Lindstrom, 
  and 
  which 
  remarkably 
  

   confirms 
  the 
  accuracy 
  of 
  the 
  drawings 
  (made 
  previously 
  to 
  our 
  seeing 
  

   the 
  cast) 
  of 
  this 
  part, 
  as 
  represented 
  by 
  fig. 
  6 
  of 
  PI. 
  XII. 
  The 
  plat- 
  

   forms 
  have 
  the 
  usual 
  scars 
  — 
  three 
  pairs 
  on 
  each 
  — 
  very 
  well 
  displayed. 
  

   The 
  postmedian 
  scar, 
  p, 
  in 
  the 
  brachial 
  valve, 
  has 
  all 
  the 
  appear- 
  

   ance 
  of 
  being 
  a 
  visceral 
  impression. 
  

  

  Dinobolus 
  Davidsoni, 
  the 
  first 
  discovered 
  form 
  among 
  the 
  Trime- 
  

   rellids, 
  was 
  erroneously 
  referred, 
  in 
  1853, 
  by 
  one 
  of 
  the 
  writers 
  to 
  

   Obolus 
  ; 
  with 
  which 
  genus 
  it 
  seemed 
  at 
  the 
  time 
  to 
  bear 
  the 
  closest 
  

   affinity, 
  especially 
  as 
  nothing 
  was 
  then 
  known 
  of 
  the 
  shells 
  composing 
  

   the 
  family 
  under 
  description. 
  

  

  From 
  near 
  Dudley,, 
  chiefly 
  as 
  internal 
  casts. 
  Mr. 
  C. 
  Ketley 
  informs 
  

   us 
  that 
  all 
  the 
  specimens 
  have 
  been 
  found 
  in 
  certain 
  beds 
  of 
  the 
  lower 
  

   or 
  " 
  thick 
  " 
  band 
  of 
  limestone 
  of 
  the 
  "Wren's 
  Nest. 
  These 
  beds 
  are 
  

   supposed 
  to 
  have 
  their 
  equivalents 
  exposed 
  at 
  the 
  Eushall 
  Canal, 
  near 
  

   "Walsall; 
  where 
  also 
  similar 
  specimens 
  were 
  obtained 
  during 
  the 
  

   cutting 
  of 
  the 
  canal 
  many 
  years 
  since. 
  At 
  Dudley 
  tunnel 
  have 
  been 
  

   found 
  a 
  few 
  specimens, 
  doubtfully 
  considered 
  to 
  be 
  D. 
  Davidsoni, 
  in 
  

   the 
  lower 
  strata. 
  Their 
  absence 
  in 
  the 
  higher 
  strata, 
  with 
  the 
  reverse 
  

   order 
  in 
  another 
  species, 
  D. 
  transversus, 
  may 
  be 
  perhaps 
  considered 
  

   worth 
  notice. 
  Tn 
  the 
  island 
  of 
  Gotland 
  it 
  is 
  very 
  abundant 
  : 
  and 
  

   in 
  rocks 
  of 
  a 
  similar 
  age, 
  near 
  Wisby, 
  slabs 
  maybe 
  seen 
  covered 
  with 
  

   scores 
  of 
  indifferently 
  perserved 
  internal 
  casts 
  and 
  impressions 
  of 
  the 
  

   shell. 
  It 
  is 
  stated 
  to 
  occur 
  at 
  Ferriters 
  Cove, 
  Kerry, 
  Ireland. 
  

  

  DlNOBOETTS 
  CANADENSIS, 
  BillillgS, 
  Sp. 
  PI. 
  XIX. 
  fig. 
  7. 
  

  

  Obolus 
  canadensis, 
  Bill. 
  Keport 
  of 
  the 
  Gool. 
  Survey 
  of 
  Canada 
  for 
  

  

  the 
  year 
  1857, 
  figs. 
  20-23 
  (not 
  fig. 
  19). 
  

   Obolellina 
  canadensis, 
  Bill. 
  Can. 
  Naturalist, 
  vol. 
  vi. 
  p. 
  222, 
  29th 
  

  

  Dec. 
  1871 
  ; 
  and 
  April 
  1872, 
  figs. 
  1-5. 
  

   Dinobolus 
  canadensis, 
  Dav. 
  & 
  King, 
  Report 
  of 
  Brighton 
  Meeting 
  

  

  of 
  Brit. 
  Assoc. 
  20th 
  August, 
  1852 
  ; 
  Annals, 
  and 
  Geol. 
  Mag. 
  for 
  

  

  same 
  year. 
  

  

  General 
  form 
  longer 
  than 
  wide. 
  Pedicle-valve 
  slightly 
  and 
  gently 
  

   convex 
  : 
  beak 
  somewhat 
  prominent 
  ; 
  very 
  slightly 
  incurved 
  : 
  area 
  

   rather 
  wide 
  : 
  deltidium 
  deeply 
  excavated*. 
  Brachial 
  valve 
  convex, 
  

   especially 
  in 
  the 
  umbonal 
  region 
  f. 
  

  

  In 
  1857 
  Mr. 
  Billings 
  included 
  in 
  the 
  present 
  species 
  both 
  elon- 
  

   gated 
  and 
  wide 
  forms 
  : 
  of 
  late, 
  however, 
  he 
  has 
  formed 
  of 
  the 
  latter 
  a 
  

   distinct 
  species, 
  the 
  next 
  but 
  two 
  under 
  description. 
  Not 
  having 
  had 
  

   the 
  advantage 
  of 
  examining 
  specimens 
  of 
  D. 
  canadensis, 
  -we 
  are 
  obliged 
  

   to 
  depend 
  entirely 
  upon 
  the 
  description 
  and 
  figures 
  of 
  it 
  published 
  by 
  

   Mr. 
  Billings. 
  As 
  now 
  restricted 
  the 
  species 
  is 
  exceptional 
  in 
  form. 
  

  

  "Width 
  usually 
  about 
  2 
  inches 
  ; 
  but 
  some 
  fragments 
  that 
  have 
  been 
  

   found 
  undoubtedly 
  belonged 
  to 
  individuals 
  which 
  were 
  3 
  inches 
  

  

  * 
  Billings 
  states 
  that 
  the 
  exterior 
  of 
  this 
  valve 
  is 
  not 
  clearly 
  shown 
  in 
  any 
  of 
  

   his 
  specimens. 
  

  

  t 
  Billings 
  has 
  figured 
  the 
  interior 
  of 
  the 
  brachial 
  valve, 
  which 
  partly 
  shows 
  

   the 
  characteristic 
  platform 
  and 
  scars. 
  

  

  