﻿126 
  T. 
  DAVIDSON 
  AND 
  W. 
  KING 
  ON 
  THE 
  TRIMERELLTDJ3. 
  

  

  On 
  the 
  20th 
  of 
  August, 
  1872, 
  the 
  writers 
  of 
  this 
  memoir 
  com- 
  

   municated 
  to 
  the 
  Geological 
  Section, 
  at 
  the 
  Brighton 
  Meeting 
  of 
  the 
  

   British 
  Association, 
  a 
  paper 
  entitled 
  " 
  Bemarks 
  on 
  the 
  genera 
  Tri- 
  

   merella, 
  Dinobolus, 
  and 
  Monomerella," 
  in 
  which 
  they 
  endeavoured 
  to 
  

   point 
  out 
  the 
  characters 
  pertaining 
  to 
  the 
  Trimerellids, 
  as 
  well 
  as 
  

   the 
  place 
  this 
  family 
  should 
  occupy 
  among 
  the 
  Palliobranchs*. 
  

  

  Before 
  concluding 
  the 
  present 
  section, 
  it 
  may 
  be 
  mentioned 
  that, 
  

   up 
  to 
  this 
  date, 
  about 
  eighteen 
  species 
  of 
  fossils 
  belonging 
  to 
  the 
  

   group 
  we 
  are 
  engaged 
  with 
  have 
  been 
  described, 
  or 
  notified, 
  and 
  that 
  

   seven 
  different 
  names 
  have 
  been 
  proposed 
  for 
  the 
  genera 
  in 
  which 
  to 
  

   include 
  them. 
  Some 
  of 
  these 
  names, 
  it 
  has 
  been 
  admitted, 
  are 
  

   synonyms, 
  or 
  belong 
  to 
  one 
  and 
  the 
  same 
  genus 
  ; 
  certain 
  others 
  have 
  

   been 
  proposed 
  for 
  groups 
  which 
  cannot, 
  we 
  think, 
  take 
  a 
  generic 
  

   rank. 
  We 
  are 
  consequently 
  led 
  to 
  restrict 
  the 
  number 
  of 
  genera 
  

   to 
  three 
  — 
  namely, 
  Trimerella, 
  Monomerella, 
  and 
  Dinobolus. 
  These 
  

   constitute 
  our 
  family 
  Trimerellidce. 
  Another 
  genus, 
  Lingulops, 
  has 
  

   been 
  proposed 
  by 
  Hall 
  for 
  a 
  curious 
  fossil 
  : 
  we 
  propose 
  giving 
  a 
  de- 
  

   scription 
  of 
  it 
  in 
  this 
  paper 
  ; 
  but 
  we 
  are 
  yet 
  undecided 
  whether 
  it 
  is 
  

   a 
  Trimerellid, 
  or 
  a 
  Lingulid. 
  

  

  .We 
  now 
  subjoin 
  a 
  list 
  of 
  the 
  species 
  : 
  — 
  

  

  Trimerella 
  grandis, 
  Billings. 
  Monomerella 
  orbicularis, 
  Bill. 
  

  

  acuminata, 
  Bill. 
  ■ 
  Lindstromi, 
  Bav. 
  $ 
  King. 
  

  

  Lindstromi, 
  Ball. 
  Dinobolus 
  Conradi, 
  Hall. 
  

  

  Billingsii, 
  Bill. 
  canadensis, 
  Bill. 
  

  

  ohioensis, 
  Meek. 
  Davidsoni, 
  Salter. 
  

  

  wisbyensis, 
  Bav. 
  fy 
  King. 
  transversus, 
  Salter. 
  

  

  galtensis, 
  Bill. 
  Woodwardi, 
  Salter. 
  

  

  Monomerella 
  Walmstedti,D«#.^"isTm§'. 
  Schmidti, 
  Bav. 
  #■ 
  King. 
  

  

  prisca, 
  Bill. 
  magnifica, 
  Bill. 
  

  

  As 
  soon 
  as 
  it 
  became 
  known 
  that 
  we 
  had 
  decided 
  on 
  preparing 
  the 
  

   present 
  memoir, 
  specimens 
  from 
  every 
  one 
  who 
  had 
  them 
  were 
  sent 
  

   to 
  us. 
  Dr. 
  Lindstrom, 
  Professors 
  Hall, 
  Fr. 
  Schmidt, 
  and 
  Walm- 
  

   stedt, 
  Messrs. 
  Fegroeus, 
  Bergman, 
  Dall, 
  Whitfield, 
  Etheridge, 
  and 
  

   Meek, 
  and 
  several 
  Dudley 
  friends 
  furnished 
  us 
  with 
  the 
  best 
  things 
  

   in 
  their 
  possession, 
  with 
  a 
  liberality 
  and 
  courtesy 
  we 
  cannot 
  forget, 
  

   as 
  did 
  also 
  Mr. 
  Billings 
  (Palaeontologist 
  of 
  the 
  Canadian 
  Geological 
  

   Survey), 
  Sir 
  W. 
  Logan, 
  and 
  Mr. 
  Selwyn. 
  To 
  all 
  we 
  beg 
  to 
  return 
  

   our 
  sincere 
  thanks. 
  

  

  II. 
  Chiefly 
  descriptive 
  oe 
  their 
  Internal 
  Parts. 
  

  

  The 
  family 
  Trimerellidce 
  includes 
  both 
  transversely 
  and 
  longitudi- 
  

   nally 
  elongated 
  species, 
  also 
  thick- 
  as 
  well 
  as 
  thin-valved 
  ones. 
  

   The 
  species 
  are 
  generally 
  of 
  considerable 
  size, 
  the 
  largest 
  known 
  

   measuring 
  nearly 
  4 
  inches 
  in 
  length. 
  Their 
  shell- 
  substance 
  is 
  

   chiefly 
  calcareous, 
  though 
  in 
  certain 
  thin 
  species 
  the 
  lime 
  may 
  

  

  * 
  Printed 
  in 
  full 
  in 
  the 
  ' 
  Brighton 
  Daily 
  News 
  ' 
  newspaper 
  for 
  the 
  21st 
  of 
  

   August, 
  1872 
  ; 
  also 
  in 
  the 
  Geol. 
  Mag. 
  vol. 
  ix. 
  Oct. 
  1872 
  ; 
  and 
  in 
  the 
  Annals 
  and 
  

   Mag. 
  of 
  Nat. 
  Hist, 
  for 
  the 
  same 
  month. 
  

  

  