﻿E. 
  8. 
  Morse 
  — 
  Fossil 
  Shells 
  in 
  Boston 
  Basin. 
  163 
  

  

  ago." 
  A 
  period 
  of 
  forty 
  years 
  passed 
  before 
  the 
  shell 
  

   appeared 
  on 
  the 
  New 
  England 
  coast. 
  In 
  a 
  paper 
  4 
  on 
  the 
  

   "Gradual 
  Dispersion 
  of 
  Certain 
  Mollnsks 
  in 
  New 
  Eng- 
  

   land/ 
  ' 
  I 
  described 
  the 
  successive 
  discoveries 
  and 
  dates 
  

   of 
  appearance 
  of 
  Litorina 
  litorea 
  along 
  the 
  New 
  England 
  

   coast. 
  C. 
  B. 
  Fuller 
  found 
  a 
  few 
  living 
  specimens 
  in 
  

   Portland 
  Harbor, 
  Maine, 
  in 
  1870, 
  and 
  in 
  that 
  year 
  found 
  

   the 
  species 
  also 
  at 
  Kennebunk, 
  Maine, 
  more 
  than 
  twenty 
  

   miles 
  farther 
  west. 
  Before 
  the 
  year 
  1872 
  it 
  had 
  never 
  

   been 
  found 
  in 
  Salem 
  Harbor. 
  In 
  that 
  year, 
  however, 
  

   Eichard 
  Rathbun 
  found 
  a 
  single 
  specimen 
  and 
  we 
  hunted 
  

  

  Fig. 
  i. 
  

  

  Fig. 
  1. 
  — 
  Fragments 
  from 
  Hull, 
  nat. 
  size. 
  

  

  for 
  hours 
  for 
  another 
  specimen 
  without 
  success. 
  In 
  a 
  

   few 
  years 
  it 
  was 
  found 
  by 
  thousands. 
  It 
  arrived 
  at 
  

   Wood's 
  Hole 
  in 
  1875 
  and 
  it 
  reached 
  New 
  Haven 
  in 
  1879. 
  

   I 
  found 
  the 
  shell 
  on 
  the 
  southern 
  shores 
  of 
  Long 
  Island 
  

   in 
  1885. 
  This 
  species, 
  now 
  the 
  most 
  abundant 
  shell 
  on 
  

   the 
  coast 
  of 
  New 
  England 
  and 
  extending 
  to 
  the 
  south 
  of 
  

   Long 
  Island 
  and 
  probably 
  much 
  farther 
  south, 
  has 
  ac- 
  

   complished 
  this 
  occupation 
  from 
  Maine 
  to 
  New 
  Haven 
  in 
  

   a 
  period 
  of 
  nine 
  years. 
  In 
  some 
  regions 
  the 
  rocks 
  are 
  

   blackened 
  by 
  their 
  numbers. 
  This 
  rapid 
  advance 
  and 
  

   enormous 
  multiplication 
  of 
  the 
  periwinkle 
  might 
  also 
  be 
  

   true 
  of 
  other 
  northern 
  species. 
  

  

  The 
  figure 
  here 
  given 
  (fig. 
  1) 
  represents 
  the 
  usual 
  ap- 
  

   pearance 
  of 
  the 
  fragments 
  of 
  Venus 
  as 
  found 
  in 
  the 
  vari- 
  

   ous 
  deposits 
  of 
  bowlder 
  clays 
  of 
  Boston 
  Basin. 
  Many 
  

   of 
  the 
  fragments 
  are 
  much 
  smaller 
  than 
  these 
  figured, 
  a 
  

   few 
  are 
  larger 
  than 
  these. 
  In 
  a 
  living 
  shell 
  the 
  radiating 
  

  

  4 
  Essex 
  Institute 
  Bulletin, 
  vol. 
  12. 
  

  

  