﻿Structure 
  of 
  Magelona. 
  411) 
  

  

  service 
  to 
  the 
  animal 
  in 
  protruding 
  its 
  anterior 
  region 
  from 
  

   the 
  sand 
  into 
  the 
  surrounding 
  water 
  for 
  aeration 
  and 
  food, 
  

   as 
  well 
  as 
  forming 
  a 
  special 
  fulcrum 
  during 
  the 
  movements 
  

   of 
  the 
  snout 
  and 
  anterior 
  region 
  in 
  boring. 
  

  

  Behind 
  the 
  preceding 
  each 
  segment 
  is 
  furnished 
  with 
  two 
  

   rows 
  of 
  hooks 
  on 
  each 
  side, 
  all 
  corresponding 
  in 
  structure, 
  

   viz. 
  winged 
  hooks 
  with 
  bifid 
  crowns, 
  the 
  most 
  anterior 
  having 
  

   the 
  larger 
  wings. 
  When 
  the 
  hooks 
  are 
  viewed 
  in 
  front 
  the 
  

   wings 
  form 
  a 
  complete 
  guard 
  by 
  uniting 
  in 
  a 
  translucent 
  

   arch 
  superiorly. 
  

  

  In 
  the 
  posterior 
  region 
  of 
  the 
  body 
  a 
  tuft 
  of 
  simple 
  curved 
  

   bristles 
  occurs 
  as 
  a 
  kind 
  of 
  support 
  to 
  each 
  pillar 
  of 
  the 
  lateral 
  

   lamellae. 
  Moreover, 
  a 
  very 
  fine 
  tuft 
  of 
  hair-like 
  bristles, 
  

   only 
  observed 
  on 
  careful 
  examination 
  in 
  the 
  living 
  animal, 
  

   projects 
  behind 
  the 
  pedicle 
  of 
  the 
  lamella 
  in 
  the 
  same 
  region. 
  

   It 
  is 
  difficult 
  to 
  believe 
  that 
  such 
  are 
  the 
  tips 
  of 
  the 
  former, 
  

   vet 
  no 
  others 
  can 
  be 
  seen 
  in 
  the 
  mounted 
  preparations. 
  Such 
  

   are 
  probably 
  homologous 
  with 
  the 
  curious 
  hidden 
  spicular 
  or 
  

   asbestos-like 
  bristles 
  in 
  Polydora. 
  

  

  In 
  the 
  first 
  region 
  of 
  the 
  body 
  the 
  bristles 
  and 
  processes 
  

   are 
  situated 
  at'the 
  extreme 
  front 
  of 
  each 
  segment, 
  near 
  the 
  

   segment-junction. 
  The 
  ninth 
  series 
  occupies 
  a 
  prominent 
  

   ridge 
  near 
  the 
  middle 
  of 
  their 
  extremely 
  short 
  segment. 
  In 
  

   the 
  posterior 
  region 
  the 
  hooks 
  are 
  placed 
  at 
  first 
  toward 
  the 
  

   anterior 
  margin 
  of 
  the 
  segment 
  ; 
  they 
  then 
  gradually 
  pass 
  

   backward 
  till 
  they 
  reach 
  the 
  posterior 
  border 
  of 
  each 
  segment 
  

   laterally. 
  

  

  The 
  anatomy 
  of 
  Magelona 
  may, 
  for 
  convenience, 
  be 
  

   arranged 
  under 
  the 
  following 
  heads 
  : 
  — 
  

  

  I. 
  The 
  Cutaneous 
  System, 
  including: 
  ]. 
  The 
  Cuticle, 
  

  

  and 
  2. 
  The 
  Hypoderm. 
  

   II. 
  The 
  Muscular 
  System. 
  

   III. 
  The 
  Digestive 
  System, 
  including 
  the 
  Proboscis. 
  

   *IV. 
  The 
  Circulatory 
  System. 
  

   * 
  V. 
  The 
  Perivisceral 
  Fluid. 
  

   VI. 
  The 
  Nervous 
  System. 
  

   VII. 
  The 
  Tentacles. 
  

   VIII. 
  The 
  Reproductive 
  System. 
  

  

  * 
  IV. 
  and 
  V. 
  have 
  already 
  been 
  translated 
  in 
  the 
  Journ. 
  Anat. 
  & 
  

   Physiol, 
  vol. 
  xiii. 
  pp. 
  331-343 
  (1879). 
  Further 
  remarks 
  may 
  by-aud-by 
  

   be 
  made, 
  especially 
  in 
  connection 
  with 
  Prof. 
  Benham'a 
  more 
  recent 
  

   researches. 
  

  

  2»* 
  

  

  