﻿10 
  HDWIN 
  S. 
  GOODRICH. 
  

  

  the 
  intestine 
  have 
  been 
  left, 
  but 
  pushed 
  aside 
  to 
  expose 
  the 
  horizontal 
  septum 
  

   and 
  ventral 
  vessel. 
  

  

  EiG. 
  2. 
  — 
  Tip 
  of 
  an 
  expanded 
  branchial 
  filament, 
  enlarged. 
  Fresh. 
  

  

  Fig. 
  3. 
  — 
  Optical 
  section 
  of 
  an 
  expanded 
  gill 
  filament, 
  enlarged. 
  Fresh. 
  

  

  Fig. 
  4. 
  — 
  Transverse 
  section 
  of 
  a 
  gill 
  filament 
  in 
  which 
  the 
  blood-vessels 
  are 
  

   partially 
  contracted. 
  Cam. 
  Z, 
  D, 
  oc. 
  3. 
  

  

  Fig. 
  5. 
  — 
  Transverse 
  section 
  of 
  the 
  posterior 
  region 
  of 
  a 
  dorsal 
  branchial 
  

   vessel, 
  in 
  a 
  semi-contracted 
  condition. 
  Cam. 
  Z. 
  D, 
  oc. 
  3. 
  

  

  Fig. 
  6. 
  — 
  Enlarged 
  view 
  of 
  the 
  outer 
  surface 
  of 
  an 
  expanded 
  anterior 
  portion 
  

   of 
  a 
  dorsal 
  branchial 
  vessel, 
  showing 
  the 
  continuous 
  contractile 
  network. 
  

   Fresh. 
  

  

  Fig. 
  7. 
  — 
  Enlarged 
  view 
  of 
  the 
  anterior 
  origin 
  of 
  some 
  of 
  the 
  dorsal 
  branchial 
  

   vessels. 
  Fresh. 
  

  

  Fig. 
  8. 
  — 
  Diagrammatic 
  figure 
  of 
  the 
  branchial 
  circulation. 
  One 
  gill 
  fila- 
  

   ment 
  is 
  expanded 
  and 
  the 
  other 
  contracted. 
  

  

  PLATE 
  3. 
  

  

  Fig. 
  9. 
  — 
  Enlarged 
  view 
  of 
  the 
  region 
  where 
  the 
  communicating 
  vessel 
  opens 
  

   into 
  the 
  dorsal 
  branchial 
  vessel, 
  in 
  optical 
  section. 
  Fresh. 
  

  

  Fig. 
  10. 
  — 
  Section 
  through 
  two 
  dorsal 
  branchial 
  vessels 
  (contracted) 
  and 
  

   the 
  accompanying 
  communicating 
  vessels, 
  showing 
  the 
  opening 
  of 
  the 
  latter 
  

   into 
  the 
  ventral 
  branchial 
  vessels. 
  Cam. 
  ^ 
  oil 
  imm., 
  oc. 
  3. 
  

  

  Fig. 
  11. 
  — 
  Section 
  through 
  the 
  same, 
  taken 
  a 
  little 
  farther 
  forward, 
  where 
  

   the 
  ventral 
  branchial 
  vessels 
  have 
  separated 
  oflT. 
  Cam. 
  jL 
  oil 
  imm., 
  oc. 
  3. 
  

  

  F'iG. 
  12. 
  — 
  Optical 
  section 
  through 
  the 
  dorsal 
  branchial 
  vessel 
  and 
  its 
  axial 
  

   rod, 
  enlarged. 
  Fresh. 
  

  

  Fig. 
  13. 
  — 
  Slightly 
  diagrammatic 
  view 
  of 
  the 
  same 
  structures. 
  

  

  Fig. 
  14. 
  — 
  Enlarged 
  view 
  of 
  the 
  anterior 
  half 
  of 
  three 
  dorsal 
  branchial 
  

   vessels. 
  Fresh. 
  

  

  Fig. 
  15. 
  — 
  Enlarged 
  optical 
  section 
  of 
  the 
  region 
  marked 
  with 
  an 
  asterisk 
  in 
  

   fig. 
  14. 
  

   Fig. 
  16. 
  — 
  Enlarged 
  view 
  of 
  two 
  amoeboid 
  cells 
  in 
  a 
  blood-vessel. 
  

  

  