﻿226 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol.96 
  

  

  Nephridia 
  4, 
  the 
  anterior 
  pair 
  close 
  behind 
  the 
  setae 
  and 
  a 
  little 
  

   farther 
  from 
  nerve 
  cord. 
  The 
  funnel 
  is 
  conspicuous, 
  with 
  an 
  undu- 
  

   lating 
  or 
  frilled 
  border, 
  but 
  is 
  not 
  prolonged 
  into 
  spiral 
  lips. 
  The 
  

   nephridia 
  of 
  all 
  specimens 
  examined 
  (taken 
  in 
  summer 
  months) 
  were 
  

   contracted. 
  In 
  some 
  cases 
  they 
  were 
  very 
  small, 
  and 
  the 
  anterior 
  

   pair 
  very 
  inconspicuous. 
  

  

  Anal 
  vesicles 
  are 
  simple, 
  elongate, 
  thin-walled 
  sacs 
  attached 
  to 
  

   ventrolateral 
  wall 
  of 
  the 
  cloaca 
  and 
  closely 
  beset 
  with 
  minute 
  ciliated 
  

   funnels. 
  

  

  Diaphragm 
  (pi. 
  20, 
  figs. 
  1, 
  4). 
  The 
  diaphragm 
  is 
  a 
  curious, 
  thin- 
  

   walled, 
  funnel-shaped 
  septum 
  incompletely 
  separating 
  the 
  peripharyn- 
  

   geal 
  coelom 
  from 
  the 
  general 
  body 
  cavity. 
  Its 
  general 
  form 
  is 
  best 
  

   appreciated 
  from 
  the 
  figure 
  in 
  which 
  it 
  is 
  shown 
  in 
  a 
  semidiagrammatic 
  

   fashion. 
  The 
  anterior, 
  rouglily 
  circular 
  edge 
  is 
  completely 
  attached 
  to 
  

   the 
  body 
  wall, 
  while 
  ventrally 
  it 
  is 
  attached 
  to 
  body 
  wall 
  on 
  each 
  side 
  

   of 
  the 
  nerve 
  cord 
  (which 
  here 
  lies 
  within 
  the 
  ventral 
  mesentery 
  of 
  

   pharynx 
  and 
  esophagus). 
  A 
  large 
  oblique 
  posterodorsal 
  opening 
  of 
  the 
  

   diaphragm 
  (with 
  complete 
  free 
  edge) 
  allows 
  the 
  esophagus 
  (with 
  its 
  

   strong 
  ventral 
  mesentery) 
  to 
  pass 
  backward 
  into 
  the 
  general 
  coelom, 
  

   sometimes 
  above 
  and 
  sometimes 
  below 
  the 
  interbasal 
  muscle. 
  The 
  

   rim 
  of 
  aperture 
  apparently 
  has 
  a 
  sphincter. 
  The 
  two 
  halves 
  of 
  the 
  

   double 
  ventral 
  mesentery 
  of 
  esophagus 
  merge 
  with 
  diaphragm 
  along 
  

   its 
  paraneural 
  part 
  and 
  a 
  short 
  distance 
  above 
  the 
  nerve 
  (pi. 
  20, 
  fig. 
  5). 
  

  

  Alimentary 
  canal. 
  The 
  pharynx 
  remains 
  always 
  in 
  the 
  peri- 
  

   pharyngeal 
  coelom. 
  It 
  is 
  attached 
  to 
  the 
  body 
  wall 
  by 
  numerous 
  strong 
  

   muscular 
  strands 
  having 
  an 
  annular 
  arrangement. 
  There 
  is 
  a 
  con- 
  

   tinuation 
  forward 
  of 
  the 
  double 
  ventral 
  and 
  dorsal 
  mesenteries 
  sep- 
  

   arated 
  into 
  frenula. 
  The 
  dorsal 
  blood 
  vessel 
  lies 
  in 
  this 
  mesenterial 
  

   complex. 
  The 
  head 
  cavity 
  is 
  therefore 
  much 
  occluded 
  by 
  tissue. 
  

   The 
  lining 
  of 
  pharynx 
  is 
  anteriorly 
  thrown 
  into 
  coarse 
  folds. 
  

  

  The 
  esophagus 
  begins 
  just 
  behind 
  the 
  region 
  of 
  the 
  radiating 
  frenula 
  

   of 
  pharynx. 
  It 
  has, 
  in 
  the 
  anterior 
  portion, 
  a 
  dorsal 
  mesentery 
  of 
  

   slender 
  separate 
  strands, 
  but 
  there 
  is 
  a 
  double 
  membranous 
  ventral 
  

   mesentery 
  throughout 
  its 
  whole 
  extent. 
  This 
  mesentery 
  is 
  anchored 
  

   in 
  the 
  peripharyngeal 
  chamber 
  on 
  each 
  side 
  of 
  the 
  nerve 
  cord, 
  where, 
  a 
  

   short 
  distance 
  above 
  body 
  wall, 
  it 
  merges 
  with 
  the 
  diaphi-agm. 
  By 
  

   means 
  of 
  its 
  muscular 
  mesenteries, 
  all 
  of 
  the 
  esophagus 
  can 
  be 
  with- 
  

   drawn 
  mto 
  the 
  head 
  cavity. 
  

  

  The 
  esophagus, 
  on 
  passing 
  through 
  the 
  right 
  side 
  of 
  the 
  diaphragm 
  

   close 
  to 
  posterior 
  border, 
  becomes 
  a 
  long 
  gizzard, 
  marked 
  by 
  rings, 
  

   which 
  are 
  prominent 
  amiular 
  ridges 
  of 
  the 
  lining. 
  Beguming 
  with 
  the 
  

   gizzard 
  the 
  alimentary 
  canal 
  is 
  moored 
  only 
  by 
  dorsal 
  mesenterial 
  

   ribbons 
  as 
  far 
  as 
  the 
  cloaca, 
  which 
  has 
  radiating 
  muscular 
  frenula. 
  

   Along 
  the 
  dorsal 
  side 
  of 
  the 
  gizzard 
  held 
  by 
  a 
  perforated 
  mesentery 
  

  

  