﻿30 
  C. 
  HERBERT 
  FOWLER. 
  

  

  only 
  visible 
  here 
  and 
  tlioie 
  ; 
  this 
  has 
  necessilated 
  a 
  sliglit 
  re-adjusf 
  ment 
  of 
  tlie 
  

   cumparat.ive 
  thicknesses 
  of 
  the 
  budv-layers 
  in 
  the 
  figures. 
  Tlie 
  ectoderm 
  has 
  

   in 
  many 
  figures 
  been 
  drawn 
  tliicker 
  th.ui 
  it 
  actually 
  appears. 
  In 
  my 
  depig- 
  

   mented 
  specimens 
  it 
  is 
  invisible 
  over 
  a 
  large 
  part 
  of 
  the 
  body 
  and 
  stalk. 
  With 
  

   the 
  exception 
  of 
  fig. 
  15, 
  all 
  outlines 
  have 
  been 
  drawn 
  with 
  the 
  Abbe 
  camera 
  

   lucida. 
  Fig. 
  15 
  is 
  ba-ed 
  on 
  a 
  plotting 
  of 
  the 
  actual 
  section-drawings 
  on 
  

   scaled 
  paper, 
  free-hand 
  curves 
  being 
  drawn 
  through 
  the 
  points 
  thus 
  obtained 
  ; 
  

   the 
  horizontal 
  scale 
  is 
  therefore 
  nearly 
  correct, 
  the 
  vertical 
  scale 
  arbitrary, 
  

   but 
  estimated 
  roughly 
  on 
  the 
  thickness 
  of 
  the 
  sections. 
  

  

  Reference 
  Letters. 
  

  

  a. 
  Streak 
  of 
  unpigmented 
  ectoderm 
  in 
  the 
  gymnocaulus 
  (? 
  nervous), 
  al. 
  

   Alimentary 
  canal, 
  asc. 
  Ascending 
  half 
  of 
  the 
  alimentary 
  canal, 
  b. 
  Space 
  in 
  

   the 
  mesentery 
  (? 
  blood-vessel 
  or 
  artificial). 
  Lc^. 
  Coelom 
  of 
  the 
  proboscis 
  or 
  

   epistome. 
  bc^. 
  Coelom 
  of 
  the 
  collar 
  region, 
  bc^. 
  Coelom 
  of 
  the 
  trunk 
  or 
  body 
  

   region, 
  caul. 
  Caulotheca, 
  or 
  stalk-pipe. 
  <;•. 
  c. 
  Cullar-canal. 
  d. 
  mes. 
  Dorsal 
  

   mesentery, 
  desc. 
  Descending 
  half 
  of 
  the 
  alimentary 
  canal, 
  ect. 
  Ectoderm. 
  

   e9id. 
  Endoderm 
  of 
  the 
  adult, 
  end. 
  ? 
  . 
  Core 
  of 
  the 
  mesentery, 
  probably 
  eudo- 
  

   dermal. 
  mes. 
  Mesentery 
  or 
  septum 
  of 
  the 
  gymnocaulus. 
  muse. 
  Longitudinal 
  

   retractor 
  muscle, 
  n. 
  Dorsal 
  thickening 
  of 
  ectoderm 
  (? 
  nerve-plate), 
  nch. 
  

   Stomodseal 
  diverticulum 
  (so 
  called 
  notochord). 
  ce. 
  ffisophagus. 
  pr. 
  Pro- 
  

   boscis, 
  r. 
  c. 
  Outline 
  of 
  a 
  human 
  red 
  blood-corpuscle, 
  for 
  scale, 
  s. 
  Septum 
  

   between 
  the 
  body-cavities 
  of 
  the 
  proboscis 
  and 
  collar, 
  st. 
  Stomodajum. 
  

   ttib. 
  Tubarium. 
  v. 
  mes. 
  Ventral 
  mesentery. 
  

  

  PLATE 
  3. 
  

  

  Figs. 
  1 
  — 
  4 
  relate 
  to 
  the 
  stalk 
  of 
  the 
  adult. 
  

  

  Eig. 
  1. 
  — 
  Section 
  of 
  the 
  posterior 
  end 
  of 
  the 
  adult, 
  at 
  the 
  point 
  of 
  flexure 
  

   of 
  the 
  intestine, 
  showing 
  the 
  continuation 
  of 
  the 
  longitudinal 
  muscle 
  of 
  

   the 
  stalk 
  on 
  to 
  the 
  body. 
  X 
  430. 
  

   Fig. 
  2.— 
  The 
  gymnocaulus, 
  below 
  the 
  body 
  of 
  the 
  animal. 
  X 
  820. 
  

   Fig. 
  3. 
  — 
  The 
  gymnocaulus, 
  at 
  the 
  commencement 
  of 
  the 
  pectocaulus. 
  

  

  X 
  820. 
  

   Fig. 
  4.— 
  The 
  pectocaulus. 
  X 
  820. 
  

   Figs. 
  5 
  — 
  14 
  are 
  successive 
  sections 
  of 
  the 
  bud 
  drawn 
  as 
  fig. 
  18. 
  The 
  plane 
  

   of 
  section 
  is 
  somewhat 
  oblique 
  and 
  the 
  epistome 
  twisted, 
  x 
  520. 
  

   Fig. 
  5. 
  — 
  Below 
  the 
  attachment 
  of 
  the 
  lophophoral 
  arms. 
  

   Fig. 
  6. 
  — 
  Through 
  the 
  highest 
  point 
  of 
  the 
  alimentary 
  canal, 
  dorsally. 
  

  

  No 
  anus 
  was 
  visible. 
  

   Fig. 
  7. 
  — 
  The 
  stomodaium, 
  open 
  on 
  the 
  right 
  side. 
  

  

  