﻿274 
  On 
  Annelida 
  Po^i/chceta 
  from 
  the 
  North 
  Sea 
  &c. 
  

  

  " 
  The 
  dorsal 
  surface 
  of 
  the 
  segments 
  sliows 
  under 
  tlie 
  micro- 
  

   scope 
  transverse 
  striae, 
  somewhat 
  irregularly 
  arranged," 
  

   The 
  proboscis 
  is 
  not 
  extruded, 
  so 
  no 
  comparison 
  with 
  M. 
  per- 
  

   armata 
  can 
  be 
  made. 
  The 
  alimentary 
  canal 
  is 
  almost 
  straight 
  

   and 
  uniform 
  for 
  the 
  first 
  seven 
  setigerous 
  segments, 
  and 
  then 
  

   it 
  assumes 
  a 
  sacculated 
  apjiearance 
  posteriorly. 
  

  

  The 
  foot 
  in 
  this 
  specimen 
  resembles 
  that 
  of 
  M. 
  perarmata 
  

   in 
  being 
  uniramous, 
  having 
  the 
  long 
  cirrus 
  dorsally 
  with 
  a 
  

   spine 
  in 
  the 
  ceratophore, 
  and 
  a 
  very 
  bluntly 
  conical 
  setigerous 
  

   region, 
  with 
  a 
  small 
  papilla? 
  supported 
  by 
  two 
  fairly 
  stout 
  

   spines, 
  and 
  carrying 
  a 
  fan-shaped 
  tuft 
  of 
  translucent 
  bristles. 
  

   The 
  articulations 
  of 
  the 
  cirrus, 
  however, 
  are 
  not 
  so 
  large 
  as, 
  

   but 
  are 
  more 
  numerous 
  than, 
  those 
  of 
  M. 
  perarmata. 
  Most 
  

   of 
  the 
  bristles 
  have 
  slightly 
  curved 
  shafts, 
  which 
  are 
  striated 
  

   and 
  have 
  a 
  bevelled 
  appearance 
  at 
  the 
  tip, 
  the 
  distal 
  end 
  of 
  

   which 
  is 
  somewhat 
  blunt, 
  and 
  in 
  several 
  of 
  those 
  whose 
  

   terminal 
  pieces 
  are 
  deeply 
  serrated 
  is 
  slightly 
  cleft 
  (see 
  

   fig. 
  2). 
  The 
  terminal 
  pieces 
  vary 
  from 
  medium 
  to 
  long. 
  

   In 
  all 
  the 
  tip 
  is 
  hooked, 
  and 
  a 
  secondary 
  process 
  is 
  present 
  

   beneath. 
  The 
  tip 
  of 
  the 
  bristles 
  in 
  M. 
  perarmata, 
  on 
  the 
  

   other 
  hand, 
  is 
  not 
  so 
  distinct, 
  for 
  it 
  is 
  only 
  in 
  the 
  shorter 
  

   forms 
  that 
  the 
  minute 
  structure 
  is 
  distinguishable. 
  The 
  

   edges 
  of 
  the 
  blades, 
  however, 
  present 
  great 
  differences. 
  In 
  

   M. 
  perarmata 
  the 
  edge 
  is 
  minutely 
  serrated 
  and 
  the 
  serrations 
  

   are 
  the 
  same 
  for 
  every 
  bristle 
  (see 
  tig. 
  3) 
  ; 
  but 
  in 
  this 
  form 
  

   the 
  serrations 
  are 
  very 
  large 
  and, 
  in 
  several 
  of 
  the 
  larger 
  

   blades, 
  resemble 
  the 
  deep 
  serrations 
  in 
  the 
  blade 
  of 
  Gastalia 
  

   fusca 
  (see 
  figs. 
  1 
  & 
  2). 
  Thus 
  two 
  distinct 
  forms 
  of 
  serration 
  

   are 
  present. 
  

  

  In 
  many 
  respects 
  the 
  animal 
  agrees 
  with 
  M. 
  perarmata, 
  

   but 
  the 
  distal 
  end 
  of 
  the 
  shafts 
  and 
  the 
  serrations 
  of 
  the 
  

   blades 
  are 
  so 
  divergent 
  and 
  diagnostic, 
  that 
  one 
  is 
  compelled 
  

   to 
  consider 
  it 
  as 
  a 
  new 
  species, 
  allied, 
  however, 
  to 
  31. 
  per- 
  

   armata. 
  The 
  specimen 
  is 
  not 
  mature. 
  Moreover, 
  it 
  is 
  an 
  

   interesting 
  feature 
  that 
  the 
  distribution 
  of 
  the 
  genus 
  has 
  

   been 
  extended 
  northward, 
  for 
  not 
  a 
  single 
  example 
  of 
  M. 
  per- 
  

   armata 
  has 
  been 
  found, 
  up 
  to 
  date, 
  north 
  of 
  Plymouth. 
  

  

  BibUographi/. 
  

  

  IIrinen. 
  1911. 
  'Die 
  Nephthydeeu 
  uiid 
  Lj'corideen 
  der 
  Nord- 
  uud 
  

  

  Ostsee.' 
  

   IzuKA. 
  1912. 
  'The 
  Errantiate 
  Polycli.ieta 
  of 
  Japan.' 
  

   Malmgren. 
  18Go. 
  ' 
  Nordiska 
  Hafs-Annulatev.' 
  Stooldiolm. 
  

   Marion 
  et 
  Bobretsky. 
  1875. 
  "Annelides 
  du 
  Golfe 
  de 
  Marseille." 
  

  

  Annales 
  des 
  Sciences 
  Naturelles, 
  sixieme 
  serie, 
  tome 
  ii. 
  

   M'Intosh. 
  1871. 
  Trans. 
  Zool. 
  Soc. 
  vol. 
  ix. 
  part 
  7. 
  "On 
  British 
  

  

  Annelida." 
  

  

  