﻿202 
  EEPOET 
  OF 
  COMMISglOKER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  pelagic 
  forms 
  are 
  not 
  onh' 
  protozoa 
  and 
  protophyta, 
  but 
  also 
  larvEe 
  of 
  

   higher 
  animals. 
  The 
  swimming 
  embryo 
  of 
  Mija 
  has 
  not 
  been 
  described 
  

   as 
  one 
  of 
  these, 
  but 
  most 
  likely 
  it 
  also 
  is 
  subject 
  to 
  destruction 
  in 
  

   this 
  way. 
  

  

  After 
  becoming 
  attached, 
  and 
  before 
  it 
  is 
  possible 
  to 
  burrow, 
  young- 
  

   clams 
  are 
  victims 
  in 
  great 
  numbers 
  to 
  the 
  rapacity 
  of 
  starfish. 
  These 
  

   pests 
  begin 
  their 
  work 
  of 
  destruction 
  while 
  very 
  young. 
  They 
  appear 
  

   in 
  the 
  early 
  summer, 
  at 
  the 
  time 
  when 
  the 
  young 
  clams 
  are 
  falling 
  

   to 
  the 
  bottom 
  and 
  struggling 
  to 
  obtain 
  a 
  lodgment. 
  Some 
  regions 
  

   are 
  much 
  more 
  subject 
  to 
  their 
  ravages 
  than 
  others. 
  Clams 
  are 
  

   not 
  produced 
  in 
  equal 
  numbers 
  every 
  year. 
  In 
  one 
  year 
  there 
  raa}^ 
  

   be 
  great 
  numbers, 
  in 
  the 
  next 
  very 
  few. 
  The 
  same 
  probably 
  is 
  

   true 
  of 
  starfish. 
  Whether 
  the 
  conditions 
  which 
  allow 
  of 
  a 
  heav}' 
  "set" 
  

   of 
  clams 
  also 
  result 
  in 
  the 
  production 
  of 
  many 
  young 
  starfish 
  is 
  not 
  

   known. 
  It 
  ma}^ 
  be 
  possible 
  that 
  this 
  is 
  not 
  always 
  so, 
  and 
  that 
  in 
  

   some 
  seasons 
  the 
  young 
  clams 
  are 
  comparatively 
  free 
  from 
  the 
  attack 
  

   of 
  their 
  arch 
  enemy. 
  But 
  some 
  young 
  starfish 
  will 
  always 
  be 
  pres- 
  

   ent, 
  and 
  a 
  few 
  are 
  capable 
  of 
  an 
  immense 
  amount 
  of 
  mischief. 
  There 
  

   is 
  no 
  doubt 
  that, 
  in 
  the 
  long 
  run, 
  the 
  struggle 
  of 
  the 
  young 
  clams 
  

   against 
  this 
  foe 
  is 
  a 
  very 
  severe 
  one. 
  

  

  A 
  few 
  gastropod 
  mollusks, 
  such 
  as 
  the 
  oyster 
  drill, 
  Urosalplniv^ 
  also 
  

   prey 
  upon 
  young 
  clams. 
  Certain 
  areas 
  have 
  been 
  noticed 
  where 
  over 
  

   30 
  per 
  cent 
  of 
  the 
  small 
  empty 
  shells 
  on 
  the 
  bottom 
  have 
  been 
  drilled, 
  

   but, 
  although 
  some 
  small 
  drilled 
  shells 
  are 
  to 
  be 
  found 
  wherever 
  young 
  

   clams 
  are 
  present, 
  the 
  losses 
  from 
  this 
  source 
  apparently 
  are 
  not 
  often 
  

   relatively 
  great. 
  Before 
  the 
  j'oung 
  clams 
  are 
  established 
  in 
  a 
  burrow, 
  

   other 
  enemies, 
  such 
  as 
  crabs 
  and 
  fishes, 
  also 
  prey 
  upon 
  them. 
  The 
  

   early 
  life 
  is 
  a 
  precarious 
  one. 
  

  

  DISTRIBUTION 
  OF 
  THE 
  YOUNG. 
  

  

  The 
  swimming 
  embryos 
  settle 
  to 
  the 
  bottom 
  between 
  and 
  below 
  the 
  

   tide-lines. 
  They 
  are 
  sown 
  with 
  a 
  prodigal 
  hand 
  in 
  shallow 
  water 
  and 
  

   in 
  deep, 
  and 
  onh^ 
  the 
  very 
  few 
  fall 
  upon 
  "good 
  ground" 
  where 
  they 
  

   may 
  have 
  a 
  chance 
  to 
  establish 
  themselves. 
  It 
  is 
  from 
  these 
  promis- 
  

   cuously 
  scattered 
  individuals 
  that 
  natural 
  beds 
  make 
  good 
  their 
  losses. 
  

   In 
  certain 
  restricted 
  localities 
  very 
  gi'eat 
  segregations 
  of 
  the 
  young 
  

   take 
  place 
  from 
  accidental 
  peculiarities 
  of 
  the 
  surroundings. 
  Their 
  

   struggle 
  for 
  existence 
  and 
  their 
  fate 
  is 
  interesting 
  and 
  instructive 
  in 
  

   many 
  ways, 
  and 
  one 
  such 
  bod, 
  which 
  was 
  observed 
  with 
  some 
  care, 
  

   will 
  be 
  described. 
  It 
  should 
  be 
  clearly 
  stated 
  that 
  these 
  thickl}^ 
  

   crowded 
  beds 
  are 
  of 
  very 
  small 
  extent 
  as 
  compared 
  with 
  natural 
  beds 
  

   of 
  mature 
  clams, 
  and 
  that 
  they 
  have 
  no 
  special 
  significance, 
  but 
  are 
  

   formed 
  where 
  conditions 
  are 
  peculiar, 
  and 
  usually 
  disappear 
  after 
  a 
  

   short 
  existence. 
  An 
  attempt 
  will 
  be 
  made 
  to 
  define 
  the 
  conditions 
  

   which 
  cause 
  these 
  peculiar 
  segregations. 
  

  

  