﻿270 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol.96 
  

  

  Alimentary 
  canal.^^ 
  — 
  As 
  indicated 
  in 
  the 
  family 
  and 
  generic 
  

   diagnoses, 
  the 
  most 
  characteristic 
  f 
  eatm-es 
  of 
  the 
  aUmentary 
  tract 
  are 
  

   the 
  extremely 
  long 
  presiphonal 
  foregut, 
  with 
  its 
  very 
  extended 
  gizzard 
  

   segment, 
  and 
  the 
  ''hind-gut" 
  modified 
  to 
  act 
  as 
  a 
  respiratory 
  organ. 
  

   These 
  features 
  are 
  closely 
  similar 
  in 
  the 
  three 
  species, 
  all 
  of 
  which 
  I 
  

   have 
  dissected. 
  The 
  apparent 
  differences 
  in 
  the 
  published 
  figures 
  

   are 
  due 
  to 
  limitations 
  of 
  material 
  or 
  faulty 
  observation. 
  In 
  plate 
  34, 
  

   figure 
  1, 
  the 
  greater 
  part 
  of 
  the 
  siphonal 
  and 
  part 
  of 
  the 
  postsiphonal 
  

   gut 
  have 
  been 
  removed, 
  A 
  very 
  contracted 
  specimen 
  was 
  used 
  owing 
  

   .to 
  limitations 
  of 
  plate. 
  Here 
  it 
  is 
  obvious 
  that 
  the 
  foregut 
  is 
  con- 
  

   siderably 
  longer 
  than 
  the 
  body. 
  In 
  a 
  well-expanded 
  preserved 
  speci- 
  

   men, 
  300 
  mm. 
  long, 
  the 
  pharynx 
  is 
  30 
  mm. 
  long; 
  esophagus 
  40 
  mm.; 
  

   crop 
  85 
  mm. 
  ; 
  gizzard 
  85 
  mm. 
  ; 
  stomach 
  50 
  mm. 
  ; 
  total 
  310 
  mm. 
  In 
  an 
  

   expanded 
  specimen 
  the 
  distance 
  between 
  the 
  position 
  of 
  the 
  stomach 
  

   and 
  anus 
  may 
  equal 
  nearly 
  one-third 
  body 
  length 
  and 
  the 
  muscular 
  

   mesentery 
  may 
  be, 
  as 
  in 
  the 
  specimen 
  under 
  discussion, 
  35 
  mm. 
  long. 
  

   The 
  posterior 
  attachment 
  of 
  this 
  mesentery 
  is 
  indicated 
  also 
  in 
  plate 
  

   36, 
  figure 
  4, 
  M\ 
  

  

  The 
  pharyngeal 
  lining 
  is 
  thrown 
  into 
  very 
  coarse 
  longitudinal 
  

   folds, 
  which 
  really 
  begin 
  on 
  the 
  ventral 
  side 
  of 
  proboscis 
  and 
  run 
  

   directly 
  to 
  the 
  esophagus, 
  diminishing 
  in 
  size. 
  In 
  the 
  esophagus 
  

   the 
  much 
  smaller 
  ridges 
  are 
  cross 
  cut 
  by 
  deep 
  narrow 
  channels, 
  which 
  

   divide 
  them 
  into 
  rings 
  of 
  oblong 
  verrucae, 
  giving 
  the 
  exterior 
  a 
  ringed 
  

   appearance. 
  The 
  esophagus 
  is 
  definitely 
  begun 
  at 
  the 
  last 
  of 
  the 
  

   dorsolateral 
  mesenteries 
  of 
  pharynx 
  (pi. 
  34, 
  fig. 
  2, 
  15). 
  In 
  this 
  

   figure 
  an 
  attempt 
  is 
  made 
  to 
  show 
  the 
  muscular 
  mesenteries 
  of 
  the 
  

   pharynx 
  by 
  a 
  view 
  looking 
  forward 
  into 
  the 
  head 
  region 
  from 
  just 
  

   back 
  of 
  the 
  first 
  pair 
  of 
  neplnidia. 
  The 
  pharynx 
  has 
  been 
  pulled 
  

   upward 
  by 
  the 
  contraction 
  of 
  these 
  dorsal 
  and 
  dorsolateral 
  mesenteries 
  

   1-7 
  (left 
  side). 
  The 
  ventral 
  mesenteries 
  {IJj) 
  are 
  the 
  least 
  variable. 
  

   Muscle 
  13 
  (paired) 
  is 
  not 
  connected 
  with 
  the 
  alimentary 
  canal 
  but 
  is 
  

   attached 
  below 
  to 
  body 
  wall 
  in 
  front 
  of 
  the 
  seta, 
  and 
  above, 
  dorso- 
  

   laterally. 
  All 
  these 
  muscular 
  mesenteries 
  are 
  characteristic 
  of 
  the 
  

   genus 
  and 
  on 
  direct 
  comparison 
  appear 
  to 
  be 
  more 
  robust 
  in 
  chilensis 
  

   except 
  13, 
  which 
  is 
  better 
  developed 
  in 
  caupo. 
  

  

  The 
  crop 
  (crop 
  1 
  of 
  Seitz) 
  is 
  subtended 
  by 
  a 
  strongly 
  muscular 
  

   mesentery 
  not 
  attached 
  to 
  body 
  wall. 
  The 
  posterior 
  part 
  of 
  esoph- 
  

   agus 
  (pi. 
  34, 
  fig. 
  1, 
  X) 
  loses 
  its 
  ringed 
  appearance, 
  the 
  mucosa 
  hav- 
  

   ing 
  deep, 
  fine, 
  longitudinal 
  folds. 
  In 
  the 
  crop 
  the 
  mucosa 
  is 
  again 
  

   regularly 
  verrucose, 
  but 
  of 
  finer 
  texture 
  than 
  in 
  esophagus. 
  In 
  the 
  

   gizzard 
  the 
  mucosa 
  is 
  thrown 
  into 
  strong 
  ring 
  folds, 
  formed 
  by 
  the 
  

   annulate 
  muscles 
  of 
  gizzard 
  wall, 
  conspicuous 
  superficially. 
  The 
  

  

  " 
  Embleton, 
  1900, 
  pi. 
  8, 
  gives 
  some 
  figures 
  of 
  the 
  histology 
  of 
  alimentary 
  canal 
  of 
  U. 
  unicinctus; 
  Seitz, 
  

   1907, 
  pi. 
  31, 
  for 
  U. 
  chilensis. 
  

  

  