﻿144 
  E. 
  J. 
  ALLEN. 
  

  

  of 
  lurg-e 
  palps 
  capable 
  of 
  great 
  elongation. 
  Mouth 
  ventral 
  

   with 
  a 
  short 
  proboscis. 
  Parapodia 
  of 
  the 
  first 
  segment 
  

   greatly 
  developed 
  and 
  directed 
  forwards, 
  provided 
  with 
  long 
  

   chastae 
  which 
  meet 
  in 
  front 
  of 
  the 
  head. 
  ParajDodia 
  with 
  well- 
  

   develoiDed 
  dorsal 
  and 
  ventral 
  cirri. 
  Cba3tfe 
  simple, 
  and 
  either 
  

   smooth 
  or 
  bearing 
  hairs 
  or 
  spines. 
  NeuroiDodia 
  of 
  the 
  second 
  

   and 
  third 
  (and 
  even 
  fourth) 
  segments, 
  with 
  three 
  or 
  four 
  

   short, 
  stout 
  bristles 
  or 
  hooks. 
  Notopodial 
  chaetee 
  of 
  the 
  

   terminal 
  segments 
  modified 
  into 
  stout, 
  strong 
  hooks 
  or 
  spikes 
  

   situated 
  on 
  the 
  dorsal 
  surface 
  of 
  the 
  body. 
  Distinct 
  posterior 
  

   (genital) 
  region 
  of 
  the 
  body 
  commencing 
  at 
  the 
  seventeenth 
  

   segment. 
  Segments 
  from 
  about 
  the 
  twentieth 
  backwards 
  

   having 
  three 
  or 
  four 
  filamentous 
  gills. 
  

  

  Genus 
  Disoma, 
  Oersted. 
  

  

  Polycheeta 
  having 
  the 
  general 
  characters 
  of 
  the 
  family 
  

   Disomida). 
  Prostomium 
  without 
  tentacles. 
  Both 
  neuropodial 
  

   and 
  notopodial 
  cirri 
  well 
  developed 
  in 
  the 
  first 
  segment. 
  

   Notopodial 
  cirri 
  from 
  the 
  third 
  to 
  the 
  sixteenth 
  segments 
  

   having 
  the 
  form 
  of 
  elongated, 
  crenated 
  plates, 
  running 
  trans- 
  

   versely 
  on 
  the 
  dorsal 
  surface. 
  Notopodial 
  and 
  neuropodial 
  

   cirri 
  from 
  segment 
  17 
  backwards 
  conical. 
  Gills 
  on 
  either 
  

   side 
  of 
  tlie 
  mid-ventral 
  line 
  commencing 
  at 
  the 
  twentieth 
  

   segment. 
  Notopodial 
  bristles 
  of 
  the 
  most 
  posterior 
  segments 
  

   stout 
  spines 
  arranged 
  in 
  star-like 
  clusters 
  on 
  the 
  dorsal 
  

   surface 
  of 
  the 
  body. 
  

  

  One 
  species 
  only 
  known 
  — 
  

  

  Disoma 
  multisetosum, 
  Oersted. 
  

   Synonyms 
  : 
  Trochochteta 
  Sarsi, 
  Levensen. 
  

  

  Thaumastoma 
  singulare, 
  Webster 
  and 
  Bene- 
  

   dict. 
  

  

  Genus 
  Pcecilochaetus, 
  Claparede. 
  

  

  Polychajta 
  having 
  the 
  general 
  characters 
  of 
  the 
  family 
  

   Disomida3. 
  Prostomium 
  with 
  one 
  anterior 
  median 
  tentacle. 
  

   Nuchal 
  organ 
  in 
  the 
  form 
  of 
  three 
  lobes 
  or 
  tentacle-like 
  

  

  