﻿NOTKS 
  ON 
  RHABDOPIiElTRA 
  NORMANT, 
  ALLMAN. 
  27 
  

  

  Figs. 
  5 
  to 
  11' 
  ai'e 
  froin 
  a 
  continuous 
  series 
  of 
  successive 
  

   sections, 
  all 
  of 
  which 
  are 
  drawn 
  ; 
  it 
  is 
  tlierefore 
  possible 
  to 
  

   follow 
  the 
  anatomy 
  minutely. 
  The 
  sections 
  are 
  slightly 
  

   oblique. 
  Starting 
  with 
  fig. 
  8, 
  there 
  seems 
  to 
  be 
  a 
  well- 
  

   marked 
  stomodaeum, 
  which, 
  owing 
  to 
  the 
  obliquity 
  of 
  the 
  sec- 
  

   tions, 
  appears 
  erroneously 
  to 
  open 
  on 
  the 
  right 
  side 
  only. 
  This 
  

   stomoda3um 
  is 
  sharply 
  separated 
  from 
  the 
  upper 
  (rectal) 
  part 
  

   of 
  the 
  alimentary 
  canal 
  by 
  a 
  stout 
  membrane 
  ; 
  the 
  canal 
  

   itself 
  at 
  this 
  level 
  appeared 
  to 
  be 
  a 
  vacuolated 
  mass, 
  in 
  which 
  

   no 
  epithelial-cell 
  outlines 
  were 
  recognised. 
  All 
  three 
  sub- 
  

   divisions 
  of 
  the 
  ccelom 
  were 
  represented 
  in 
  this 
  section 
  — 
  a 
  

   small 
  pait 
  of 
  the 
  proboscis-cavity 
  {he}), 
  the 
  left 
  collar- 
  

   cavity 
  (bc.~), 
  and 
  the 
  trunk-cavity, 
  apparently 
  divided 
  into 
  

   two 
  parts 
  by 
  the 
  alimentary 
  canal 
  dorsally 
  and 
  ventrally 
  

   (bc.^). 
  On 
  the 
  animaPs 
  right 
  side 
  the 
  section 
  passed 
  nearly 
  

   along 
  the 
  septum 
  between 
  the 
  collar- 
  and 
  trunk-cavities. 
  

  

  In 
  the 
  section 
  above 
  this 
  (fig. 
  7) 
  the 
  collar-cavity 
  of 
  the 
  

   right 
  side 
  appeared, 
  and 
  the 
  trunk-cavity 
  of 
  that 
  side 
  had 
  

   almost 
  vanished. 
  The 
  next 
  section 
  upwards 
  (fig. 
  6) 
  was 
  un- 
  

   fortunately 
  folded 
  between 
  proboscis 
  and 
  coeloni, 
  so 
  that 
  not 
  

   more 
  than 
  has 
  been 
  drawn 
  could 
  be 
  recognised 
  ; 
  it 
  was 
  

   obvious, 
  however, 
  that 
  the 
  stomodteal 
  groove 
  of 
  the 
  previous 
  

   section 
  had 
  been 
  folded 
  off 
  as 
  a 
  rod, 
  which 
  contained 
  (1 
  think) 
  

   a 
  cavity. 
  In 
  the 
  highest 
  section 
  figured 
  (fig. 
  5) 
  the 
  alimentary 
  

   canal 
  was 
  no 
  longer 
  met 
  with 
  ; 
  the 
  rod 
  of 
  the 
  previous 
  

   section 
  was 
  in 
  the 
  position 
  of 
  the 
  notochord. 
  

  

  Passing 
  downwards 
  from 
  fig. 
  8, 
  the 
  next 
  section 
  (also 
  

   folded 
  at 
  the 
  attachment 
  of 
  the 
  proboscis) 
  showed 
  a 
  thick 
  

   muscle-band 
  on 
  the 
  outer 
  wall 
  of 
  the 
  right-hand 
  half 
  of 
  the 
  

   trunk 
  body-cavity, 
  other 
  structures 
  remaining 
  much 
  as 
  before 
  

   (fig. 
  9), 
  In 
  fig. 
  10 
  the 
  stomodteum 
  had 
  entered 
  the 
  alimentary 
  

   canal 
  [oe), 
  and 
  the 
  lower 
  lip 
  had 
  been 
  reached. 
  In 
  fig. 
  11 
  

   the 
  right 
  trunk 
  bod^^-cavity 
  had 
  increased 
  considerably 
  in 
  

   size, 
  and 
  the 
  attachment 
  of 
  the 
  proboscis 
  had 
  been 
  passed. 
  

   The 
  left 
  collar-cavity 
  had 
  all 
  but 
  disappeared 
  in 
  fig. 
  12; 
  the 
  

   left 
  trunk-cavity 
  showed 
  its 
  longitudinal 
  muscle, 
  and 
  a 
  septum 
  

   separated 
  the 
  two 
  trunk-cavities 
  ventrally. 
  In 
  fig. 
  13 
  the 
  

  

  