﻿79 
  

  

  ON 
  RAETOMYA, 
  A 
  NEW 
  GENUS 
  OF 
  PELECYPODA, 
  FROM 
  THE 
  

   TEETIARY 
  ROCKS 
  OF 
  EGYPT 
  AND 
  SOUTHERN 
  NIGERIA. 
  

  

  By 
  11. 
  BuLLEN 
  Neavton, 
  F.G.S.' 
  

  

  Bead 
  14th 
  June, 
  1918. 
  

  

  PLATE 
  I. 
  

  

  The 
  shell 
  described 
  in 
  this 
  paper 
  was 
  originally 
  found 
  in 
  the 
  Upper 
  

   Mokattam 
  Beds 
  (= 
  Eocene) 
  of 
  Egypt, 
  while 
  further 
  examples 
  of 
  the- 
  

   same 
  have 
  now 
  been 
  identified 
  from 
  Southern 
  Nigerian 
  rocks 
  

   contained 
  in 
  collections 
  made 
  by 
  Dr. 
  A. 
  E. 
  Kitson, 
  F.G.S., 
  Principal 
  

   of 
  the 
  Mineral 
  Survey 
  of 
  the 
  Gold 
  Coast, 
  and 
  Sir 
  J. 
  Eaglesome, 
  

   C.M.G., 
  both 
  of 
  whom 
  have 
  presented 
  their 
  specimens 
  to 
  the 
  

   Geological 
  Department 
  of 
  the 
  British 
  Museum, 
  Dr. 
  Kitson's 
  liaving 
  

   been 
  presented 
  in 
  association 
  with 
  W. 
  Heward 
  Bell, 
  Esq., 
  F.G.S. 
  

  

  A 
  preliminary 
  collection 
  of 
  fossils 
  from 
  the 
  same 
  locality, 
  but 
  

   containing 
  no 
  remains 
  of 
  the 
  shell 
  in 
  question, 
  was 
  obtained 
  and 
  

   also 
  presented 
  to 
  that 
  institution 
  by 
  Sir 
  F. 
  Lugard, 
  G.C.M.G. 
  The 
  

   fossils 
  acquired 
  in 
  this 
  manner 
  between 
  the 
  years 
  1915 
  and 
  1917 
  

   were 
  discovered 
  in 
  the 
  same 
  section, 
  which 
  is 
  situated 
  on 
  the 
  Port 
  

   Harcourt 
  Railway, 
  Onibialla 
  District 
  of 
  Southern 
  Nigeria. 
  They 
  

   belong 
  chiefly 
  to 
  the 
  invertebrate 
  groups, 
  especially 
  the 
  Mollusca, 
  

   although 
  relics 
  of 
  some 
  important 
  vertebrates 
  consisting 
  of 
  a 
  zeuglo- 
  

   dont, 
  bird 
  and 
  chelouian 
  remains, 
  fishes, 
  etc., 
  are 
  also 
  represented, 
  

   which 
  have 
  been 
  already 
  partially 
  described 
  by 
  Dr. 
  A. 
  S. 
  "Woodward,^ 
  

   F.B.S., 
  and 
  Dr. 
  C. 
  W. 
  Andrews,^ 
  F.R.S., 
  who 
  are 
  both 
  of 
  opinion 
  

   that 
  they 
  belong 
  to 
  an 
  Eocene 
  age, 
  and 
  probably 
  the 
  older 
  part 
  of 
  

   that 
  formation 
  as 
  suggested 
  by 
  the 
  second 
  author, 
  on 
  account 
  of 
  some 
  

   particular 
  characters 
  shown 
  by 
  the 
  zeuglodont 
  remains. 
  

  

  Until 
  further 
  studies 
  are 
  completed 
  on 
  the 
  molluscan 
  fauna 
  it 
  is 
  

   considered 
  premature 
  to 
  offer 
  too 
  definite 
  a 
  statement 
  as 
  to 
  tlie 
  

   geological 
  age 
  of 
  the 
  deposits, 
  although, 
  in 
  the 
  meantime, 
  it 
  may 
  be 
  

   mentioned 
  that 
  they 
  present 
  a 
  very 
  similar 
  lithological 
  facies 
  which 
  

   would 
  suggest 
  their 
  reference 
  to 
  one 
  distinct 
  series 
  of 
  beds, 
  and 
  

   which 
  from 
  their 
  fauna 
  would 
  indicate 
  an 
  estuariue 
  origin. 
  The 
  

   matrix 
  is 
  a 
  grey 
  and 
  greenish-grey 
  calcareous 
  sandstone 
  of 
  variable 
  

   degrees 
  of 
  hardness, 
  sometimes 
  assuming 
  the 
  density 
  and 
  appearance 
  

   of 
  flint 
  which 
  frequently 
  forms 
  the 
  infilling 
  material 
  of 
  the 
  

   Pelecypod 
  valves, 
  thus 
  rendering 
  it 
  difficult 
  for 
  the 
  development 
  of 
  

   internal 
  characters. 
  With 
  regard 
  to 
  the 
  specifi^c 
  form, 
  Lovellia 
  

   schweinfurthi, 
  which 
  constitutes 
  the 
  type 
  of 
  the 
  new 
  genus 
  described 
  

   in 
  this 
  paper, 
  it 
  is 
  only 
  right 
  to 
  state 
  that 
  it 
  fully 
  supports 
  the 
  

   Eocene 
  age 
  theory 
  for 
  the 
  Nigerian 
  beds 
  as 
  hitherto 
  recognized, 
  on 
  

   account 
  of 
  its 
  occurrence 
  in 
  the 
  Upper 
  Mokattam 
  deposits 
  of 
  Egypt, 
  

   which 
  belong 
  to 
  the 
  Lutetian 
  or 
  Middle 
  stage 
  of 
  the 
  European 
  

  

  ^ 
  Published 
  by 
  permission 
  of 
  the 
  Trustees 
  of 
  the 
  British 
  Museum. 
  

   2 
  Abstracts 
  Proc. 
  Geol. 
  See. 
  London, 
  No. 
  989, 
  1916, 
  p. 
  51. 
  

   ' 
  Abstracts 
  Proc. 
  Zool. 
  Soc. 
  London, 
  No. 
  158, 
  1916, 
  p. 
  30, 
  and 
  Proc. 
  Zool. 
  Soc. 
  

   London, 
  1916, 
  pp. 
  519-24, 
  figs. 
  1-4. 
  

  

  