﻿OYSTEE 
  INDUSTRY 
  OF 
  NORTH 
  CAROLINA. 
  

  

  285 
  

  

  or 
  in 
  a 
  given 
  quantity 
  of 
  water 
  was 
  much 
  less 
  than 
  the 
  number 
  of 
  

   individuals 
  of 
  the 
  other 
  important 
  species, 
  Eupodiscus 
  nevertheless 
  

   represented 
  more 
  real 
  nutriment 
  than 
  they, 
  as 
  will 
  be 
  shown 
  farther 
  on. 
  

   Pleurosigma 
  spencerli 
  (fio'. 
  7), 
  is 
  an 
  S-shaped 
  species 
  which 
  lives 
  

   and 
  multiplies 
  at 
  the 
  surface 
  of 
  the 
  mud 
  flats 
  of 
  both 
  the 
  Beaufort 
  

   and 
  Pamlico 
  Sound 
  regions. 
  It 
  becomes 
  especially 
  abundant 
  during 
  

   the 
  hot 
  summer 
  months 
  and 
  furnishes 
  the 
  principal 
  part 
  of 
  the 
  

   food 
  of 
  o3"sters 
  in 
  the 
  vicinity 
  of 
  the 
  flats. 
  It 
  is 
  less 
  abvmdant, 
  both 
  

   in 
  the 
  water 
  and 
  in 
  the 
  oysters' 
  stomachs, 
  the 
  farther 
  from 
  muddy 
  

   bottoms 
  the 
  specimens 
  are 
  collected, 
  and 
  the 
  quantity 
  available 
  from 
  

  

  Outline 
  drawings 
  of 
  the 
  principal 
  constituents 
  of 
  the 
  food 
  of 
  North 
  Carolina 
  oysters. 
  

  

  1. 
  Navicula 
  didyma. 
  6. 
  Eupodiscus 
  radiatus. 
  

  

  2. 
  Diatoma 
  sp? 
  7. 
  Pleurosigma 
  spencerii. 
  

  

  3. 
  Prorocentrum 
  sp? 
  8. 
  Melosira 
  sp? 
  

  

  •4. 
  Heterocapsa 
  sp? 
  9. 
  Melosira 
  sculpta. 
  

  

  5. 
  Glenodinium 
  sp? 
  10. 
  Coscinodiscus 
  perforatus. 
  

  

  year 
  to 
  jear 
  varies 
  considerably, 
  as 
  may 
  be 
  seen 
  by 
  reference 
  to 
  the 
  

   food 
  tables 
  on 
  pages 
  289-90. 
  The 
  cause 
  of 
  this 
  variation 
  is 
  not 
  clear. 
  

   In 
  the 
  Beaufort 
  region 
  the 
  diatom 
  was 
  least 
  abundant 
  during 
  the 
  very 
  

   wet 
  season 
  of 
  1901 
  and 
  was 
  most 
  plentiful 
  during 
  the 
  drought 
  of 
  1900, 
  

   yet 
  in 
  Wyesocking 
  Bay 
  just 
  the 
  reverse 
  was 
  true. 
  

  

  Navicula 
  didyma 
  (fig. 
  1), 
  is 
  8-shaped 
  and, 
  like 
  the 
  preceding 
  species, 
  

   is 
  motile 
  and 
  lives 
  at 
  the 
  surface 
  of 
  mud 
  flats. 
  It 
  is 
  easily 
  taken 
  up 
  

   and 
  carried 
  about 
  by 
  the 
  water, 
  and 
  usually 
  forms 
  a 
  very 
  appreciable 
  

   part 
  of 
  the 
  diet 
  of 
  oysters 
  both 
  in 
  the 
  Beaufort 
  and 
  Pamlico 
  Sound 
  

   regions. 
  

  

  