﻿426 
  PR0CEEDINQ8 
  OF 
  THE 
  NATIONAL 
  MUSEUM, 
  vol.44. 
  

  

  surface 
  of 
  the 
  trunk 
  in 
  the 
  larger 
  specimen 
  is 
  blocked 
  off 
  into 
  rectan- 
  

   gular 
  elevations 
  by 
  the 
  contractions 
  of 
  the 
  underlying 
  muscles. 
  _ 
  

  

  The 
  introvert, 
  which 
  is 
  shorter 
  than 
  the 
  trunk, 
  is 
  cylindrical, 
  

   and 
  covered 
  with 
  exceedingly 
  minute, 
  slender, 
  recurved 
  hooks, 
  which 
  

   can 
  not 
  be 
  seen 
  easily 
  with 
  a 
  magnification 
  of 
  less 
  than 
  60 
  diameters. 
  

  

  The 
  posterior 
  end 
  of 
  the 
  retractor 
  muscle 
  (fig. 
  15) 
  is 
  divided, 
  and 
  

   the 
  two 
  roots 
  (representing 
  the 
  right 
  and 
  left 
  ventral 
  retractors) 
  are 
  

   inserted 
  on 
  each 
  side 
  of 
  the 
  posterior 
  shield. 
  A 
  muscle 
  strand 
  extends 
  

   to 
  the 
  body 
  wall 
  from 
  the 
  retractor 
  immediately 
  in 
  front 
  of 
  the 
  angle 
  

   between 
  the 
  diverging 
  roots. 
  The 
  longitudinal 
  muscles 
  of 
  the 
  body 
  

   wall 
  form 
  a 
  continuous 
  layer. 
  The 
  long, 
  slender 
  nephridia 
  are 
  

   attached 
  by 
  a 
  fold 
  of 
  peritoneum 
  to 
  the 
  body 
  wall. 
  The 
  intestine 
  

   makes 
  a 
  coil 
  of 
  about 
  10 
  wide 
  turns, 
  and 
  is 
  supported 
  by 
  a 
  very 
  strong 
  

   spindle 
  muscle. 
  The 
  ventral 
  nerve 
  cord 
  projects 
  prominently 
  into 
  

   the 
  body 
  cavity. 
  

  

  This 
  form 
  somewhat 
  resembles 
  A. 
  mirahilis 
  Theel 
  of 
  the 
  west 
  coast 
  

   of 
  Norway 
  and 
  Sweden, 
  but, 
  aside 
  from 
  size, 
  it 
  differs 
  from 
  it 
  in 
  the 
  

   smoothness 
  of 
  the 
  trunk, 
  the 
  presence 
  of 
  prominent 
  spines 
  on 
  the 
  

   anterior 
  shield, 
  the 
  attachment 
  of 
  the 
  nephridia 
  by 
  folds 
  of 
  perito- 
  

   neum, 
  and 
  other 
  less 
  marked 
  features. 
  

  

  ASPIDOSIPHON 
  SPECIOSUS, 
  new 
  species. 
  

  

  Key 
  West, 
  Florida, 
  shore 
  (?). 
  One 
  specimen. 
  

  

  Type.— 
  Cat. 
  No. 
  16320, 
  U.S.N.M. 
  

  

  Station 
  2336, 
  off 
  Havana, 
  lat. 
  23° 
  10' 
  48" 
  N. 
  ; 
  long. 
  82° 
  18' 
  52" 
  W.; 
  

   157 
  fathoms, 
  coral 
  bottom. 
  One 
  specimen. 
  

  

  Station 
  2758, 
  east 
  of 
  Brazil, 
  lat. 
  6° 
  59' 
  30" 
  S.; 
  long. 
  34° 
  47' 
  W.; 
  

   20 
  fathoms, 
  broken 
  shells; 
  temperature 
  at 
  surface 
  and 
  bottom, 
  79° 
  F. 
  

   One 
  specimen. 
  

  

  Distinctive 
  features. 
  — 
  Introvert 
  nearly 
  or 
  quite 
  as 
  long 
  as 
  the 
  

   trunk 
  (pi. 
  62, 
  fig. 
  22). 
  About 
  110 
  rows 
  of 
  fine, 
  single-pointed 
  hooks 
  

   (fig. 
  16) 
  on 
  the 
  first 
  fifth 
  of 
  the 
  introvert. 
  Introvert 
  and 
  middle 
  

   of 
  the 
  trunk 
  smooth. 
  Ends 
  of 
  the 
  trunk 
  covered 
  with 
  polygonal 
  

   elevations. 
  Both 
  shields 
  furrowed 
  (pi. 
  62, 
  fig. 
  22). 
  Longitudinal 
  

   muscle 
  layer 
  discontinuous. 
  A 
  transverse 
  septum 
  stretches 
  across 
  

   the 
  coelom 
  in 
  front 
  of 
  the 
  anus 
  and 
  the 
  nephridia. 
  Ventral 
  

   retractor 
  muscles 
  fused 
  into 
  one. 
  No 
  eye-spots. 
  

  

  The 
  trunk 
  of 
  the 
  specimen 
  from 
  Key 
  West 
  is 
  40 
  mm. 
  in 
  length, 
  the 
  

   introvert 
  38-40 
  mm. 
  in 
  length. 
  The 
  spines 
  on 
  the 
  posterior 
  part 
  of 
  

   the 
  introvert 
  are 
  exceedingly 
  fine 
  and 
  the 
  introvert 
  is 
  smooth. 
  The 
  

   anterior 
  and 
  posterior 
  ends 
  of 
  the 
  trunk 
  are 
  covered 
  with 
  polygonal 
  

   or 
  squarish 
  elevations 
  of 
  a 
  dark-brown 
  color 
  on 
  a 
  grayish 
  field. 
  The 
  

   middle 
  portion 
  (nearly 
  one-half 
  the 
  length) 
  of 
  the 
  trunk 
  is 
  smooth 
  

   and 
  of 
  a 
  yellowish-brown 
  color. 
  The 
  shields 
  are 
  dark 
  bro\vn 
  and 
  

   furrowed. 
  The 
  anterior 
  shield 
  is 
  oval, 
  with 
  its 
  long 
  axis 
  transverse, 
  

   with 
  18 
  short 
  and 
  long 
  furrows 
  at 
  its 
  posterior 
  edge, 
  converging 
  as 
  

  

  