﻿90 
  E. 
  J. 
  ALLEN. 
  

  

  neuropodial 
  cirri. 
  These 
  cirri 
  are 
  flask 
  shaped, 
  but 
  the 
  basal 
  

   part 
  of 
  each 
  cirrus 
  or 
  body 
  of 
  the 
  flask 
  becomes 
  swollen 
  and 
  

   almost 
  spherical, 
  whilst 
  the 
  neck 
  is 
  thin, 
  elongated 
  and 
  

   nearly 
  cylindrical, 
  with 
  a 
  slight 
  enlargement 
  at 
  the 
  distal 
  

   end. 
  The 
  whole 
  cirrus, 
  including 
  the 
  neck, 
  is 
  very 
  rigid, 
  

   being 
  much 
  less 
  flexible 
  than 
  the 
  cirri 
  of 
  the 
  other 
  segments, 
  

   and 
  only 
  moves 
  from 
  its 
  base 
  at 
  the 
  point 
  of 
  attachment 
  to 
  

   the 
  body 
  of 
  the 
  worm. 
  The 
  stiff 
  movement 
  of 
  the 
  cirri 
  gives 
  

   a 
  characteristic 
  appearance 
  to 
  this 
  region 
  of 
  the 
  body 
  in 
  the 
  

   living 
  worm. 
  The 
  cheetse 
  in 
  these 
  segments 
  are 
  of 
  two 
  kinds, 
  

   smooth, 
  slender 
  hairs 
  (PI. 
  9, 
  fig. 
  13)^ 
  which 
  show 
  longi- 
  

   tudinal 
  striation 
  under 
  a 
  high 
  power, 
  and 
  spiny 
  bristles 
  

   (PI. 
  7, 
  figs. 
  4 
  and 
  5 
  ; 
  PL 
  9, 
  fig. 
  15), 
  the 
  number 
  of 
  the 
  latter 
  

   being 
  few 
  in 
  each 
  bundle. 
  

  

  Lateral 
  sense-organs 
  in 
  the 
  form 
  of 
  pear-shaped 
  papillas 
  

   are 
  still 
  found 
  between 
  the 
  cirri, 
  but 
  the 
  bases 
  of 
  the 
  papillte, 
  

   where 
  they 
  are 
  attached 
  to 
  the 
  parapodium, 
  are 
  bi'oader 
  than 
  

   in 
  the 
  more 
  anterior 
  segments. 
  

  

  In 
  segments 
  14, 
  15 
  and 
  16 
  (PI. 
  9, 
  fig. 
  9) 
  the 
  parapodia 
  

   have 
  a 
  structure 
  more 
  nearly 
  resembling 
  that 
  found 
  in 
  the 
  

   fourth 
  and 
  sixth 
  segments. 
  The 
  cirri 
  are 
  shorter 
  and 
  stouter, 
  

   nearly 
  conical 
  in 
  shape, 
  and 
  are 
  without 
  tho 
  long 
  stiff 
  necks 
  

   found 
  in 
  the 
  segments 
  immediately 
  in 
  front. 
  The 
  chaetEe 
  

   remain 
  of 
  two 
  kinds, 
  as 
  in 
  the 
  latter 
  segments, 
  and 
  the 
  lateral 
  

   sense-organ 
  still 
  protrudes 
  from 
  the 
  surface 
  of 
  the 
  para- 
  

   podium. 
  

  

  With 
  segment 
  17 
  there 
  is 
  again 
  a 
  change, 
  but 
  the 
  structure 
  

   then 
  found 
  continues 
  in 
  its 
  essential 
  features, 
  with 
  the 
  

   exception 
  of 
  the 
  addition 
  of 
  gill 
  filaanents 
  commencing 
  at 
  

   segment 
  21, 
  until 
  about 
  thirty 
  segments 
  from 
  the 
  end 
  of 
  the 
  

   body. 
  

  

  Both 
  the 
  notopodial 
  and 
  neuropodial 
  cirri, 
  conical 
  in 
  shape, 
  

   are 
  now 
  much 
  smaller 
  in 
  size 
  (figs. 
  1, 
  10, 
  and 
  11), 
  and 
  vary 
  

   considerably 
  and 
  somewhat 
  irregularly 
  in 
  the 
  extent 
  to 
  which 
  

   they 
  are 
  developed 
  from 
  segment 
  to 
  segment. 
  

  

  There 
  is, 
  on 
  the 
  other 
  hand, 
  a 
  very 
  remarkable 
  development 
  

   of 
  the 
  chaette. 
  In 
  both 
  notopodium 
  and 
  neuropodium 
  the 
  

  

  