﻿420 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  vol.44. 
  

  

  The 
  20-28 
  short 
  tentacles, 
  standing 
  in 
  two 
  lateral 
  rows, 
  do 
  not 
  encircle 
  

   the 
  mouth, 
  but 
  arc 
  situated 
  on 
  the 
  dorsal 
  side 
  of 
  it, 
  encircled 
  by 
  a 
  

   low 
  collar 
  of 
  integument 
  opening 
  dorsally. 
  

  

  The 
  musculature 
  is 
  strong; 
  the 
  longitudinal 
  muscle 
  layer 
  is 
  split 
  

   into 
  about 
  30 
  (26-32) 
  anastomosing 
  bands, 
  and 
  the 
  circular 
  muscle 
  

   layer 
  also 
  tends 
  to 
  form 
  bands. 
  Four 
  strong 
  retractors, 
  of 
  which 
  the 
  

   ventral 
  are 
  attached 
  in 
  the 
  posterior, 
  the 
  dorsal 
  in 
  the 
  anterior 
  part 
  of 
  

   the 
  middle 
  third 
  of 
  the 
  trunk; 
  and 
  those 
  of 
  the 
  same 
  side 
  are 
  united 
  

   only 
  in 
  the 
  anterior 
  part 
  of 
  the 
  introvert. 
  Two 
  large 
  eye-spots. 
  In- 
  

   testinal 
  coil 
  with 
  few 
  whorls, 
  with 
  a 
  complete 
  columellar 
  muscle 
  and 
  

   a 
  single 
  fastener 
  ventral 
  to 
  the 
  esophagus 
  and 
  the 
  first 
  whorl. 
  Rectum 
  

   of 
  medium 
  length. 
  Contractile 
  tube 
  simple, 
  only 
  0.24 
  mm. 
  thick. 
  

   Nephridia 
  very 
  long, 
  fastened 
  by 
  a 
  mesentery 
  along 
  the 
  anterior 
  

   third. 
  Eggs 
  (0.12 
  mm.) 
  with 
  a 
  thin 
  yolk 
  membrane 
  pierced 
  with 
  

   fine 
  pore 
  canals. 
  Trunk 
  35 
  mm., 
  introvert 
  42 
  mm. 
  

  

  The 
  structure 
  of 
  this 
  very 
  variable 
  species 
  has 
  been 
  well 
  described 
  

   by 
  Shipley 
  (1890). 
  

  

  PHYSCOSOMA 
  ANTILLARUM 
  (Grube 
  and 
  Orsted). 
  

  

  Phascolosoma 
  fuscum 
  Keferstein, 
  1862. 
  

   Phascolosoma 
  nvjriceps 
  Baird, 
  1868. 
  

  

  Key 
  West, 
  Florida, 
  cavities 
  in 
  rocks 
  between 
  tides 
  (Henry 
  Hemp- 
  

   hill, 
  1885). 
  Five 
  specimens. 
  

  

  This 
  species 
  has 
  been 
  foimd 
  among 
  the 
  West 
  Indies 
  at 
  ^luriel, 
  

   Cuba 
  (U. 
  S. 
  Nat. 
  Mus., 
  Palmer 
  and 
  RUey), 
  St. 
  Croix 
  (Grube 
  and 
  

   Orsted), 
  St. 
  Thomas 
  (Keferstein), 
  Barbados 
  (Stuttgart 
  Museum, 
  

   Selenka; 
  U. 
  S. 
  Nat. 
  Mus., 
  Worthing, 
  Barbados, 
  on 
  reef, 
  (H. 
  M. 
  

   Lefroy) 
  and 
  Jamaica 
  (Baii'd) 
  ; 
  off 
  the 
  adjacent 
  mainland 
  of 
  Colombia, 
  

   Sabanilla, 
  and 
  Venezuela 
  (U. 
  S. 
  Nat. 
  Mus., 
  Albatross, 
  1884), 
  at 
  Puerto 
  

   Cabello 
  (Grube), 
  and 
  Pernambuco 
  and 
  Goyanna, 
  Brazil 
  (U. 
  S. 
  Nat. 
  

   Mus., 
  A. 
  W. 
  Greeley). 
  In 
  the 
  Pacific, 
  it 
  has 
  been 
  found 
  on 
  the 
  coast 
  

   of 
  Costa 
  Rica 
  at 
  Puntarenas 
  (Grube 
  and 
  Orsted) 
  and 
  on 
  the 
  coast 
  of 
  

   Chile 
  (Baird). 
  

  

  The 
  following 
  description 
  is 
  based 
  largely 
  on 
  Keferstein' 
  s 
  account, 
  

   as 
  given 
  by 
  Selenka 
  (1883), 
  which 
  agrees 
  closely 
  with 
  the 
  facts 
  as 
  I 
  

   have 
  found 
  them: 
  

  

  Distinctive 
  features. 
  — 
  Introvert 
  one-half 
  to 
  one- 
  third 
  the 
  length 
  of 
  

   the 
  trunk 
  (pi. 
  62, 
  fig. 
  20), 
  which 
  in 
  a 
  partially 
  contracted 
  specimen 
  is 
  

   four 
  or 
  five 
  times 
  as 
  long 
  as 
  thick 
  (pi. 
  62, 
  fig. 
  19). 
  The 
  thick 
  skin 
  is 
  

   everywhere 
  covered 
  with 
  prominent, 
  flat, 
  dark-brown 
  papiHee 
  be- 
  

   tween 
  which 
  the 
  whitish 
  or 
  yellowish 
  skin 
  appears. 
  PapillfB 
  at 
  the 
  

   posterior 
  end 
  of 
  the 
  trunk 
  and 
  especially 
  at 
  the 
  base 
  of 
  the 
  introvert 
  

   are 
  large, 
  rough, 
  and 
  dark-colored, 
  forming 
  at 
  the 
  anterior 
  extremity 
  

   black 
  plates 
  separated 
  only 
  by 
  naiTow 
  fissures. 
  On 
  the 
  introvert 
  

   the 
  papillae 
  are 
  further 
  separated 
  and 
  are 
  conical 
  vnth 
  a 
  sharp 
  apex. 
  

  

  