﻿MANUAL 
  OF 
  FISH-CULTURE. 
  227 
  

  

  Development 
  takes 
  place 
  in 
  Avater 
  ranging 
  in 
  temperature 
  between 
  

   33° 
  and 
  55° 
  F., 
  the 
  time 
  of 
  incubation 
  varying 
  from 
  about 
  40 
  days 
  at 
  the 
  

   former 
  temperature 
  to 
  11 
  or 
  12 
  days 
  at 
  the 
  latter. 
  Sudden 
  and 
  extreme 
  

   variation 
  between 
  the 
  temperature 
  limits 
  mentioned 
  had 
  little 
  or 
  no 
  

   effect 
  except 
  to 
  retard 
  or 
  accelerate 
  the 
  hatching 
  in 
  accordance 
  with 
  

   the 
  rule 
  just 
  mentioned. 
  When 
  water 
  of 
  a 
  temperature 
  lower 
  than 
  

   33° 
  F. 
  was 
  used 
  many 
  of 
  the 
  embryos 
  were 
  deformed. 
  The 
  degree 
  of 
  

   salinity 
  of 
  the 
  water 
  does 
  not 
  appear 
  to 
  exert 
  much 
  iuHueuce 
  ui)on 
  the 
  

   hatching 
  of 
  the 
  eggs. 
  

  

  THE 
  SAND-DAB 
  AND 
  FOUR-SPOTTED 
  FLOUNDER. 
  

  

  Besides 
  the 
  flatfish 
  or 
  winter 
  flounder, 
  two 
  other 
  flounders 
  have 
  been 
  

   artificially 
  hatched, 
  on 
  a 
  small 
  scale, 
  at 
  Woods 
  Hole; 
  these 
  are 
  the 
  

   sand-dab 
  {Bothus 
  maculatus) 
  and 
  the 
  four-spotted 
  flounder 
  {raraUchtJiys 
  

   oblongus). 
  The 
  eggs 
  of 
  both 
  fish 
  are 
  buoyant, 
  and 
  deposited 
  in 
  May. 
  

   Those 
  of 
  the 
  former 
  are 
  .f^ 
  inch 
  in 
  diameter, 
  and 
  of 
  the 
  latter 
  ^^ 
  inch. 
  

   The 
  period 
  of 
  incubation 
  at 
  a 
  temperature 
  varying 
  from 
  51° 
  to 
  54° 
  F. 
  

   is 
  about 
  8 
  days. 
  

  

  