﻿E. 
  S. 
  Morse 
  — 
  Fossil 
  Shells 
  in 
  Boston 
  Basin. 
  165 
  

  

  ribs 
  do 
  not 
  show 
  between 
  the 
  lines 
  of 
  growth, 
  only 
  after 
  

   great 
  abrasion 
  of 
  the 
  shell 
  or 
  decomposition 
  of 
  the 
  sur- 
  

   face 
  as 
  in 
  the 
  shell 
  of 
  Venus 
  mercenaria 
  exposed 
  by 
  dig- 
  

   ging 
  a 
  trench 
  in 
  a 
  marsh 
  in 
  Salem 
  are 
  the 
  radial 
  markings 
  

   visible. 
  These 
  features 
  also 
  show 
  in 
  the 
  same 
  species 
  

   which 
  came 
  up 
  in 
  the 
  dredgings 
  in 
  Portland 
  Harbor. 
  

   The 
  thickness 
  of 
  the 
  shell 
  is 
  shown 
  in 
  the 
  middle 
  outline 
  

   though 
  much 
  thicker 
  specimens 
  are 
  seen. 
  

  

  In 
  examining 
  the 
  collection 
  of 
  shells 
  made 
  by 
  Scudder 
  

   from 
  the 
  Sankaty 
  deposits 
  I 
  found 
  a 
  marked 
  difference 
  

   in 
  the 
  quohaugs. 
  There 
  were 
  many 
  perfect 
  specimens 
  of 
  

   the 
  Venus 
  mercenaria 
  all 
  of 
  uniform 
  size 
  showing 
  traces 
  

   of 
  the 
  purple 
  markings 
  inside 
  the 
  shell. 
  These 
  were 
  

   light 
  brownish 
  in 
  color 
  as 
  if 
  stained 
  with 
  iron. 
  The 
  

   larger 
  and 
  thicker 
  shells 
  in 
  fragments 
  with 
  no 
  stain 
  

   of 
  purple 
  represent 
  the 
  variety 
  designated 
  by 
  Verrill 
  as 
  

   var. 
  antiqua. 
  These 
  I 
  believe 
  to 
  be 
  V. 
  campechiensis. 
  

   The 
  broken 
  edges 
  of 
  the 
  shells 
  do 
  not 
  show 
  the 
  slightest 
  

   signs 
  of 
  wear. 
  

  

  I 
  may 
  add 
  that 
  the 
  fragments 
  of 
  shells 
  from 
  Point 
  

   Shirley 
  seem 
  much 
  larger 
  than 
  those 
  collected 
  at 
  Hull 
  

   and 
  it 
  may 
  be 
  that 
  as 
  the 
  clay 
  pushed 
  much 
  farther 
  at 
  

   Hull 
  the 
  shells 
  were 
  more 
  broken 
  and 
  ground 
  than 
  those 
  

   nearer 
  the 
  place 
  of 
  origin. 
  

  

  I 
  wish 
  to 
  thank 
  Mrs. 
  George 
  L. 
  Chaney 
  of 
  Salem 
  for 
  

   the 
  Florida 
  Venus, 
  fig. 
  2. 
  

  

  