﻿62 
  PEOCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  [Nov. 
  18, 
  

  

  marked 
  by 
  concentric 
  striae, 
  which 
  are 
  crossed 
  by 
  fine 
  longitudinal 
  

   radiating 
  lines. 
  The 
  muscular 
  scars 
  are 
  scarcely 
  distinguishable. 
  

  

  The 
  recent 
  Tellina 
  jplicata 
  appears 
  to 
  be 
  closely 
  related 
  to 
  this 
  

   fossil, 
  which 
  is 
  very 
  well 
  marked 
  in 
  consequence 
  of 
  the 
  two 
  posterior 
  

   ribs 
  being 
  not 
  merely 
  plications 
  in 
  the 
  shell, 
  as 
  is 
  the 
  case 
  in 
  so 
  many 
  

   species 
  of 
  the 
  genus. 
  

  

  Matrix. 
  — 
  The 
  casts 
  are 
  composed 
  of 
  a 
  reddish 
  sandy 
  clay. 
  

  

  22. 
  CULTELLUS 
  (?), 
  Sp. 
  

  

  Three 
  portions 
  of 
  internal 
  casts, 
  each 
  representing 
  something 
  less 
  

   than 
  half 
  of 
  a 
  very 
  elongated 
  shell, 
  probably 
  belong 
  to 
  the 
  genus 
  

   Cultellus, 
  or 
  to 
  one 
  of 
  its 
  subgenera. 
  The 
  casts 
  are 
  elongated 
  and 
  

   compressed, 
  rounded 
  and 
  slightly 
  gaping 
  at 
  the 
  ends, 
  and 
  concentri- 
  

   cally 
  wrinkled 
  towards 
  the 
  extremities. 
  Pallia! 
  sinus 
  probably 
  short, 
  

   acutely 
  angular, 
  and 
  not 
  very 
  wide. 
  The 
  shell 
  was 
  nearly 
  equilateral. 
  

  

  One 
  of 
  the 
  specimens 
  represents 
  the 
  posterior 
  portion 
  of 
  the 
  shell, 
  

   the 
  remaining 
  two 
  the 
  anterior 
  region 
  ; 
  the 
  former 
  is 
  marked 
  by 
  a 
  

   very 
  oblique 
  channel, 
  extending 
  from 
  near 
  the 
  umbo 
  almost 
  to 
  the 
  

   end. 
  This 
  may 
  possibly 
  represent 
  an 
  umbonal 
  rib, 
  but 
  it 
  may 
  only 
  

   correspond 
  to 
  a 
  plication 
  in 
  the 
  shell. 
  The 
  only 
  species 
  having 
  such 
  

   an 
  oblique 
  groove 
  is, 
  I 
  believe, 
  Solen 
  uniradiatus, 
  Bellardi 
  *, 
  in 
  which, 
  

   however, 
  it 
  is 
  much 
  more 
  oblique, 
  and 
  appears 
  to 
  be 
  caused 
  merely 
  

   by 
  a 
  plication 
  on 
  the 
  shell, 
  and 
  not 
  to 
  be 
  a 
  definite 
  structure 
  like 
  

   the 
  umbonal 
  rib 
  of 
  Machcera. 
  

  

  Matrix. 
  — 
  Similar 
  to 
  that 
  of 
  the 
  Tellina, 
  but 
  more 
  sandy. 
  

  

  23. 
  Amphistegiista 
  vulgaris, 
  d'Orb. 
  

  

  Two 
  specimens 
  of 
  this 
  Foraminifer 
  occurred 
  in 
  the 
  matrix 
  of 
  

   Natica 
  rostalina. 
  For 
  their 
  identification 
  I 
  am 
  indebted 
  to 
  Prof. 
  

   T. 
  Eupert 
  Jones, 
  F.G.S., 
  who 
  considers 
  that 
  this 
  form 
  and 
  the 
  Mio- 
  

   cene 
  A. 
  Haueri, 
  as 
  well 
  as 
  A. 
  Lessonii 
  and 
  A. 
  gibbosa, 
  are 
  merely 
  

   varieties 
  of 
  one 
  species. 
  

  

  III. 
  Coxclttsioh". 
  

  

  1. 
  Emigration 
  Eastwards 
  of 
  the 
  European 
  Miocene 
  Fauna 
  and 
  its 
  

   influence 
  on 
  the 
  Contemporaneity 
  of 
  Tertiary 
  Formations. 
  — 
  Before 
  

   discussing 
  the 
  probable 
  age 
  of 
  the 
  Mount 
  Sela 
  deposit, 
  the 
  question 
  

   of 
  the 
  contemporaneity 
  of 
  Tertiary 
  strata 
  in 
  different 
  parts 
  of 
  the 
  

   world 
  requires 
  a 
  little 
  consideration. 
  

  

  It 
  will 
  be 
  admitted 
  that 
  if 
  two 
  Tertiary 
  formations, 
  geographically 
  

   distant 
  from 
  one 
  another, 
  contained 
  the 
  same 
  proportion 
  of 
  recent 
  

   species, 
  that 
  one 
  would 
  be 
  the 
  newer 
  whose 
  species 
  bore 
  the 
  greatest 
  

   resemblance 
  to 
  the 
  fauna 
  of 
  the 
  neighbouring 
  seas, 
  unless 
  it 
  could 
  

   be 
  proved 
  that 
  great 
  physical 
  changes 
  had 
  recently 
  occurred 
  in 
  the 
  

   one 
  area 
  and 
  not 
  in 
  the 
  other. 
  Consequently, 
  if 
  two 
  Tertiary 
  for- 
  

   mations 
  contain 
  about 
  the 
  same 
  proportion 
  of 
  recent 
  forms, 
  and 
  an 
  

   emigration 
  of 
  species 
  to, 
  or 
  continued 
  existence 
  of 
  them 
  in, 
  one 
  area 
  

   can 
  be 
  shown 
  to 
  have 
  occurred, 
  that 
  formation 
  is 
  certainly 
  the 
  newer 
  

  

  * 
  " 
  Catalogo 
  ragionato 
  dei 
  Fossili 
  Numnmlitici 
  d'Egitto," 
  di 
  L. 
  Bellardi, 
  

   Mem.fEeale 
  Accad. 
  delle 
  Scienze 
  di 
  Torino, 
  ser. 
  2, 
  toI. 
  xv. 
  p. 
  184. 
  pi. 
  2. 
  fig. 
  5. 
  

  

  