﻿244 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  103 
  

  

  and 
  14. 
  Although 
  no 
  mature 
  sexual 
  buds 
  were 
  found 
  attached 
  to 
  the 
  

   stem 
  form, 
  the 
  rudiments 
  of 
  the 
  notopodia 
  with 
  the 
  developing 
  swim- 
  

   ming 
  setae 
  could 
  be 
  seen, 
  beginning 
  on 
  setiger 
  7. 
  Male 
  and 
  female 
  

   stolons 
  with 
  six 
  anterior 
  unmodified 
  segments 
  were 
  found. 
  Of 
  these, 
  

   two 
  female 
  stolons 
  showed 
  the 
  characteristic 
  banding 
  of 
  A. 
  prismaticus 
  

   (this 
  banding 
  was 
  noted 
  on 
  aU 
  the 
  developing 
  sexual 
  buds 
  still 
  attached 
  

   to 
  the 
  stem 
  forms 
  of 
  this 
  species). 
  The 
  others 
  did 
  not 
  show 
  this 
  

   banding 
  and 
  are 
  considered 
  to 
  be 
  the 
  sexual 
  stolons 
  of 
  A. 
  jallax. 
  A. 
  

   Jallax, 
  then, 
  along 
  with 
  A. 
  prismaticus, 
  has 
  six 
  anterior, 
  unmodified 
  

   setigers 
  and 
  manj^ 
  of 
  the 
  records 
  of 
  A. 
  prismaticus 
  in 
  the 
  literature 
  

   will 
  no 
  doubt 
  prove 
  to 
  be 
  A. 
  jallax. 
  

  

  The 
  stem 
  form 
  of 
  A. 
  fallax 
  has 
  been 
  referred 
  to 
  A. 
  prolijer 
  (Miiller) 
  

   by 
  Augener 
  (1913, 
  1928) 
  and 
  Wesenberg-Lund 
  (1947), 
  thus 
  the 
  stem 
  

   form 
  of 
  A. 
  fallax 
  has 
  been 
  confused 
  wdth 
  A. 
  prolifer 
  and 
  sexual 
  forms 
  

   with 
  A. 
  prismaticus. 
  

  

  There 
  appears 
  to 
  be 
  a 
  correlation 
  in 
  the 
  place 
  of 
  formation 
  of 
  the 
  

   sexual 
  stolons 
  in 
  the 
  stem 
  form 
  with 
  the 
  number 
  of 
  anterior, 
  unmodi- 
  

   fied 
  setigers 
  and 
  the 
  number 
  of 
  tentacular 
  cirri 
  in 
  the 
  sexual 
  stolons. 
  

   At 
  least 
  for 
  a 
  group 
  of 
  species, 
  including 
  A. 
  prismaticus, 
  A. 
  fallax, 
  A. 
  

   cornutus 
  A. 
  Agassiz, 
  and 
  A. 
  ornatus 
  (Verrill, 
  1873), 
  the 
  stem 
  forms 
  

   produce 
  sexual 
  stolons 
  singly, 
  with 
  the 
  head 
  of 
  the 
  stolon 
  forming 
  

   between 
  setigers 
  13 
  and 
  14. 
  The 
  stolon, 
  then, 
  consists 
  of 
  the 
  segments 
  

   of 
  the 
  stem 
  posterior 
  to 
  setiger 
  13 
  (differing 
  from 
  A. 
  prolifer 
  where 
  

   the 
  sexual 
  stolons 
  are 
  proliferated 
  more 
  posteriorly, 
  often 
  in 
  chains 
  of 
  

   2 
  to 
  8). 
  The 
  posterior 
  part 
  develops 
  gradually 
  into 
  the 
  male 
  or 
  

   female 
  sexual 
  stolon 
  and 
  breaks 
  off 
  when 
  mature. 
  The 
  anterior 
  13 
  

   setigers 
  of 
  the 
  stem 
  regenerates 
  another 
  posterior 
  end. 
  The 
  sexual 
  

   stolons 
  of 
  these 
  four 
  species 
  have 
  six 
  mimodified 
  setigers 
  anterior 
  to 
  

   the 
  swimming 
  setae 
  and 
  usually 
  a 
  more 
  or 
  less 
  developed 
  immodified 
  

   posterior 
  region. 
  The 
  stolons 
  have 
  three 
  pairs 
  of 
  tentacular 
  cirri 
  on 
  

   the 
  first 
  two 
  achaetous 
  tentacular 
  segments; 
  the 
  first 
  two 
  pairs 
  on 
  the 
  

   first 
  segment 
  and 
  the 
  third 
  pair 
  on 
  the 
  second 
  segment. 
  The 
  upper 
  

   pair 
  of 
  tentacular 
  cirri 
  on 
  the 
  first 
  segment 
  are 
  similar 
  to 
  the 
  dorsal 
  

   cirri. 
  The 
  lower 
  pair 
  may 
  be 
  very 
  short, 
  about 
  the 
  length 
  of 
  the 
  

   prostomium. 
  The 
  third 
  pair 
  of 
  tentacular 
  cirri 
  in 
  the 
  female 
  are 
  

   similar 
  to 
  the 
  dorsal 
  cirri; 
  in 
  the 
  male 
  they 
  are 
  very 
  long, 
  similar 
  to 
  

   the 
  median 
  antenna. 
  In 
  addition, 
  there 
  are 
  a 
  pair 
  of 
  small 
  achaetous 
  

   lobes. 
  In 
  contrast, 
  in 
  A. 
  prolifer 
  the 
  sexual 
  stolons 
  have 
  three 
  ante- 
  

   rior 
  unmodified 
  setigers 
  (sometimes 
  two 
  or 
  four) 
  and 
  a 
  poorly 
  devel- 
  

   oped 
  posterior 
  region; 
  there 
  is 
  a 
  single 
  tentacular 
  achaetous 
  segment 
  

   with 
  two 
  pairs 
  of 
  tentacular 
  cirri 
  (in 
  the 
  female 
  both 
  the 
  upper 
  and 
  

   lower 
  pairs 
  are 
  short; 
  in 
  the 
  male 
  the 
  lower 
  one 
  is 
  similar 
  to 
  the 
  dorsal 
  

   cirri 
  and 
  the 
  upper 
  one 
  is 
  very 
  long, 
  similar 
  to 
  the 
  median 
  antenna). 
  

   In 
  A. 
  alexandri 
  the 
  sexual 
  stolons 
  have 
  14 
  (sometimes 
  13) 
  anterior 
  

  

  