﻿418 
  JOURNAL 
  OF 
  THE 
  WASHINGTON 
  ACADEMY 
  OF 
  SCIENCES 
  VOL. 
  12, 
  NO. 
  18 
  

  

  eighteen 
  microns 
  wide, 
  is 
  distinctly 
  set 
  off 
  by 
  constriction; 
  and 
  espe- 
  

   cially 
  laterally, 
  on 
  account 
  of 
  the 
  large 
  and 
  conspicuous 
  amphids, 
  lo- 
  

   cated 
  just 
  at 
  the 
  base 
  of 
  the 
  lip 
  region. 
  The 
  pharynx 
  is 
  entered 
  

   through 
  a 
  vestibule, 
  more 
  or 
  less 
  hexagonal 
  when 
  closed, 
  about 
  nine 
  

   microns 
  long 
  and 
  at 
  its 
  narrowest 
  part, 
  when 
  the 
  lips 
  are 
  at 
  rest, 
  

   normally 
  not 
  over 
  one 
  micron 
  wide. 
  The 
  pharynx, 
  like 
  other 
  parts 
  

   of 
  the 
  anatomy, 
  is 
  distinctly 
  dorylaimoid, 
  but 
  the 
  very 
  small 
  left 
  

   ventrally 
  submedian 
  tooth-like 
  onchium, 
  only 
  six 
  microns 
  long 
  and 
  one 
  

   and 
  one-half 
  microns 
  wide 
  at 
  the 
  base, 
  instead 
  of 
  being 
  tubular, 
  as 
  

   in 
  Dorylaimus, 
  is 
  closed. 
  The 
  food 
  does 
  not 
  pass 
  through 
  it, 
  but 
  to 
  one 
  

   side. 
  Speaking 
  broadly 
  the 
  pharynx 
  is 
  of 
  double 
  structure, 
  — 
  ^the 
  

   anterior 
  portion 
  being 
  somewhat 
  napiform 
  or 
  fusiform, 
  and 
  the 
  pos- 
  

   terior 
  more 
  or 
  less 
  tubular 
  or 
  prismoid. 
  To 
  go 
  into 
  particulars, 
  the 
  

   pharynx 
  may 
  be 
  said 
  to 
  be 
  divided 
  into 
  four 
  parts, 
  arranged 
  tandem, 
  

   reached 
  through 
  a 
  narrow 
  vestibule 
  from 
  the 
  somewhat 
  flaring 
  mouth 
  

   opening. 
  Part 
  one, 
  the 
  shortest 
  part, 
  about 
  five 
  microns 
  long, 
  extends 
  

   from 
  the 
  vestibule 
  to 
  the 
  region 
  opposite 
  the 
  apex 
  of 
  the 
  solid 
  onchium, 
  

   and 
  might 
  be 
  regarded 
  as 
  a 
  portion 
  of 
  the 
  vestibule. 
  This 
  portion 
  

   of 
  the 
  pharynx 
  is 
  characterized 
  by 
  the 
  presence 
  in 
  its 
  wall 
  of 
  several 
  

   short 
  longitudinal 
  ribs 
  or 
  refractive 
  folds, 
  no 
  doubt 
  six 
  in 
  number. 
  

   The 
  second 
  portion 
  of 
  the 
  pharynx, 
  a 
  little 
  

  

  longer 
  than 
  the 
  preceding 
  and 
  with 
  it 
  form- 
  ^«^ 
  . 
  - 
  ' 
  ^^'^'^'* 
  

   ing 
  a 
  broadly 
  fusiform 
  cavity, 
  is 
  the 
  portion 
  fflpost^ 
  vw^ 
  

  

  of 
  the 
  pharynx 
  containing 
  the 
  onchium, 
  and 
  /** 
  \^^'~ 
  W 
  

  

  is 
  lined 
  throughout 
  the 
  greater 
  portion 
  of 
  its 
  om/i 
  V 
  ^ 
  .^ 
  ^> 
  

  

  length 
  with 
  a 
  multitude 
  of 
  excessively 
  fine 
  lobMsuM^^- 
  i./ 
  

  

  denticles, 
  apparently 
  similar 
  to 
  those 
  found 
  Fig. 
  2. 
  Front 
  view 
  of 
  the 
  lip 
  

   in 
  the 
  pharynx 
  of 
  some 
  mononchs, 
  and, 
  as 
  ^^g^onoi 
  NygoMmus 
  ienticulatus 
  

  

  ^ 
  ■> 
  n.sp. 
  ppl 
  ant, 
  ppl 
  post, 
  anterior 
  

  

  there, 
  shghtly 
  larger 
  and 
  more 
  regular 
  ante- 
  ^^^ 
  posterior 
  labial 
  papillae 
  ; 
  ph, 
  

   riorly. 
  The 
  third 
  portion, 
  eleven 
  microns 
  pharynx; 
  amph, 
  amphid; 
  loh 
  

   long, 
  is 
  the 
  anterior 
  third 
  of 
  the 
  tubular 
  ^"^ 
  ^"^'"' 
  '^* 
  '^'^ 
  ^"*"?' 
  ventrally 
  

  

  . 
  , 
  , 
  1 
  M 
  J 
  1 
  r 
  . 
  1 
  1 
  and 
  dorsally 
  submedian 
  lobes 
  of 
  

  

  part 
  of 
  the 
  pharynx, 
  while 
  the 
  fourth 
  and 
  ^^^^^^ 
  ^^^.^^. 
  ^„ 
  „^,hium. 
  

   longest 
  portion, 
  twenty 
  microns 
  long, 
  is 
  

  

  the 
  posterior 
  two-thirds 
  of 
  that 
  tube. 
  Thus 
  the 
  entire 
  pharynx 
  is 
  

   nearly 
  sixty 
  microns 
  long. 
  The 
  distinction 
  between 
  parts 
  three 
  and 
  

   four 
  is 
  not 
  very 
  marked 
  ; 
  it 
  manifests 
  itself 
  in 
  the 
  varying 
  refractivity 
  

   of 
  the 
  lining 
  of 
  the 
  two 
  parts, 
  and 
  also 
  in 
  the 
  tendency 
  of 
  the 
  posterior 
  

   part 
  to 
  be 
  more 
  prismoid 
  or 
  cylindroid, 
  while 
  the 
  anterior 
  third 
  tapers 
  

   slightly 
  from 
  front 
  to 
  back. 
  The 
  thickness 
  of 
  the 
  various 
  parts 
  of 
  the 
  

   highly 
  refractive 
  walls 
  of 
  the 
  pharynx 
  is 
  somewhat 
  variable, 
  — 
  from 
  a 
  

  

  