﻿TWO 
  NEW 
  LARVAL 
  NEMATODES 
  BELONGING 
  TO 
  THE 
  

  

  GENUS 
  PORROCAECUM 
  FROM 
  MAMMALS 
  OF 
  THE 
  

  

  ORDER 
  INSECTIVORA 
  

  

  By 
  Benjamin 
  Schwartz 
  

  

  Of 
  the 
  Zoological 
  Division, 
  Bureau 
  of 
  Animal 
  Industry, 
  United 
  States 
  

   Department 
  of 
  Agriculture 
  

  

  Under 
  date 
  of 
  October 
  22, 
  1924, 
  Dr. 
  Paul 
  Bartsch 
  of 
  the 
  United 
  

   States 
  [National 
  Museum, 
  forwarded 
  to 
  this 
  laboratory 
  encysted 
  lar- 
  

   val 
  nematodes, 
  collected 
  by 
  Miss 
  F. 
  A. 
  Cook 
  from 
  under 
  the 
  skin 
  of 
  

   a 
  short-tailed 
  shrew 
  (Blarina 
  brevicauda) 
  in 
  the 
  District 
  of 
  Colum- 
  

   bia. 
  The 
  cysts 
  are 
  spherical 
  in 
  shape, 
  from 
  2 
  mm. 
  to 
  4 
  mm. 
  in 
  maxi- 
  

   mum 
  diameter, 
  each 
  containing 
  a 
  spirally 
  coiled 
  nematode, 
  visible 
  

   through 
  the 
  rather 
  transparent 
  cyst 
  wall. 
  Two 
  nematodes 
  were 
  freed 
  

   from 
  their 
  cysts 
  by 
  dissecting 
  the 
  cyst 
  wall 
  and 
  several 
  cysts 
  were 
  

   cleared 
  without 
  injuring 
  the 
  cyst 
  wall. 
  Examination 
  of 
  the 
  worms 
  

   showed 
  that 
  though 
  they 
  were 
  sexually 
  immature, 
  they 
  could 
  be 
  

   readily 
  identified 
  as 
  belonging 
  to 
  the 
  genus 
  Porrocaecum, 
  on 
  the 
  

   basis 
  of 
  the 
  oblong 
  esophageal 
  ventriculus, 
  the 
  absence 
  of 
  an 
  eso- 
  

   phageal 
  appendix, 
  and 
  the 
  presence 
  of 
  an 
  intestinal 
  cecum. 
  

  

  Owing 
  to 
  the 
  feeble 
  development 
  of 
  the 
  lips 
  and 
  accessory 
  mouth 
  

   structures 
  in 
  the 
  worms 
  in 
  question 
  it 
  is 
  neither 
  possible 
  nor 
  desirable 
  

   to 
  assign 
  them 
  to 
  any 
  of 
  the 
  known 
  species 
  of 
  the 
  genus, 
  and 
  follow- 
  

   ing 
  a 
  common 
  usage 
  among 
  zoologists, 
  these 
  parasites, 
  though 
  sex- 
  

   ually 
  immature 
  and 
  otherwise 
  incompletely 
  developed, 
  are 
  given 
  

   specific 
  rank, 
  the 
  name 
  Pon-ocaecum 
  encapsu7atum 
  being 
  proposed 
  

   for 
  them. 
  

  

  PORROCAECUM 
  ENCAPSULATUM, 
  new 
  species 
  

  

  Immature 
  worms, 
  occurring 
  in 
  globular 
  cysts 
  from 
  2 
  mm. 
  to 
  4 
  mm. 
  

   in 
  maximum 
  diameter, 
  lodged 
  under 
  the 
  skin 
  of 
  the 
  host. 
  The 
  

   worms 
  are 
  long, 
  slender, 
  superficially 
  resembling 
  filaria, 
  lying 
  

   spirally 
  coiled 
  within 
  their 
  cysts 
  (fig. 
  8). 
  The 
  cuticle 
  is 
  striated 
  

   transversely 
  throughout 
  the 
  entire 
  length 
  of 
  the 
  worms. 
  One 
  speci- 
  

   men 
  extracted 
  from 
  the 
  cyst 
  measures 
  36 
  mm. 
  in 
  length 
  by 
  0.365 
  mm. 
  

   in 
  maximum 
  width. 
  The 
  head 
  when 
  viewed 
  from 
  the 
  side 
  shows 
  

  

  No. 
  2589.— 
  Proceedings 
  U. 
  S. 
  National 
  Museum, 
  Vol. 
  67, 
  Art. 
  17 
  

  

  29111— 
  Uo 
  1 
  

  

  