﻿E. 
  8. 
  Morse 
  — 
  Fossil 
  Shells 
  in 
  Boston 
  Basin. 
  161 
  

  

  size 
  and 
  massive 
  character, 
  and 
  considers 
  the 
  variety 
  so 
  

   distinct 
  as 
  to 
  warrant 
  naming 
  it 
  var. 
  antiqua 
  Verrill, 
  and 
  

   says, 
  "By 
  this 
  name 
  I 
  propose 
  to 
  designate 
  the 
  unusu- 
  

   ally 
  massive 
  and 
  strongly 
  sculptured 
  variety 
  to 
  which 
  

   most 
  of 
  the 
  fossil 
  shells 
  belong." 
  

  

  The 
  ponderous 
  character 
  of 
  Venus 
  mercenaria 
  as 
  indi- 
  

   cated 
  by 
  the 
  thickness 
  of 
  the 
  fragments 
  first 
  arrested 
  my 
  

   attention 
  in 
  collections 
  made 
  at 
  Hull, 
  and 
  Moon 
  Island. 
  

   It 
  is 
  somewhat 
  curious 
  that 
  Stimpson, 
  who 
  first 
  wrote 
  on 
  

   the 
  subject, 
  makes 
  no 
  allusion 
  to 
  this 
  conspicuous 
  fea- 
  

   ture 
  of 
  the 
  shell. 
  In 
  a 
  very 
  ancient 
  shellheap 
  in 
  Japan 
  

   I 
  discovered 
  that 
  there 
  were 
  differences 
  between 
  the 
  

   ancient 
  shells 
  composing 
  the 
  deposits 
  and 
  the 
  recent 
  

   forms 
  living 
  in 
  Yedo 
  Bay. 
  All 
  varied 
  in 
  their 
  pro- 
  

   portional 
  diameters. 
  I 
  reasoned 
  that 
  if 
  any 
  physical 
  

   conditions 
  of 
  climate, 
  temperature, 
  etc., 
  had 
  changed 
  

   Venus 
  mercenaria 
  so 
  profoundly, 
  other 
  species 
  in 
  the 
  

   bowlder 
  clay 
  should 
  vary 
  likewise, 
  but 
  only 
  the 
  slightest 
  

   changes 
  were 
  observed 
  in 
  the 
  few 
  species 
  I 
  studied. 
  A 
  

   study 
  of 
  a 
  gigantic 
  Venus 
  from 
  Florida, 
  for 
  a 
  long 
  time 
  

   known 
  as 
  Venus 
  Mortoni 
  of 
  Conrad, 
  but 
  bearing, 
  at 
  last 
  

   accounts, 
  the 
  name 
  of 
  Venus 
  campechiensis 
  , 
  a 
  shell 
  found 
  

   in 
  the 
  upper 
  Tertiary 
  of 
  the 
  southern 
  states 
  and 
  living 
  

   as 
  far 
  north 
  as 
  Chesapeake 
  Bay, 
  leads 
  me 
  to 
  believe 
  that 
  

   the 
  bowlder 
  clay 
  species 
  which 
  has 
  always 
  been 
  identified 
  

   as 
  Venus 
  mercenaria 
  may 
  prove 
  to 
  be 
  the 
  southern 
  form 
  

   Venus 
  campechiensis. 
  A 
  colony 
  of 
  quohaugs 
  living 
  in 
  

   Maine 
  at 
  Quohaug 
  Bay, 
  near 
  Freeport, 
  may 
  also 
  be 
  

   Venus 
  campechiensis. 
  The 
  shell 
  is 
  much 
  larger 
  and 
  

   thicker 
  than 
  the 
  usual 
  V 
  . 
  mercenaria, 
  though 
  not 
  so 
  large 
  

   as 
  V. 
  campechiensis, 
  has 
  the 
  same 
  rounded 
  form 
  of 
  the 
  

   Florida 
  species 
  and 
  has 
  no 
  tinge 
  of 
  purple 
  which 
  is 
  so 
  

   marked 
  a 
  character 
  of 
  V 
  . 
  mercenaria. 
  Is 
  it 
  not 
  possi- 
  

   ble 
  that 
  all 
  these 
  forms 
  may 
  prove 
  to 
  be 
  geographical 
  

   variations 
  of 
  V. 
  mercenaria? 
  

  

  The 
  fossil 
  beds 
  regarded 
  as 
  post-pliocene 
  at 
  Sankaty 
  

   Head, 
  on 
  the 
  eastern 
  end 
  of 
  Nantucket, 
  have 
  been 
  care- 
  

   fully 
  studied 
  by 
  Verrill, 
  Scudder, 
  and 
  Rathbun, 
  and 
  

   before 
  these 
  men 
  Desor 
  and 
  Cabot. 
  Prof. 
  A. 
  E. 
  Verrill, 
  

   in 
  the 
  interesting 
  communication 
  already 
  referred 
  to, 
  in 
  

   which 
  is 
  incorporated 
  Dr. 
  S. 
  H. 
  Scudder 
  's 
  careful 
  study 
  

   of 
  the 
  deposits, 
  gives 
  a 
  complete 
  list 
  of 
  the 
  fossils 
  shells 
  

   collected 
  by 
  Rathbun 
  and 
  identified 
  by 
  himself, 
  with 
  com- 
  

   ments 
  on 
  their 
  distributions 
  along 
  the 
  coast 
  to-day. 
  It 
  

  

  