﻿242 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol.96 
  

  

  specimens, 
  varying 
  from 
  less 
  than 
  one-third 
  to 
  the 
  full 
  length 
  of 
  body. 
  

   Four 
  nephridia, 
  the 
  nephrostome 
  with 
  very 
  long 
  coiled 
  lips. 
  Siphon 
  

   begins 
  a 
  short 
  distance 
  behind 
  the 
  ring 
  blood 
  vessel 
  (marking 
  the 
  

   boundary 
  between 
  foregut 
  and 
  intestine) 
  ; 
  anal 
  vesicles 
  long, 
  with 
  

   pointed 
  apex 
  and 
  with 
  tiny 
  ciliated 
  funnels 
  scattered 
  over 
  surface; 
  

   setae 
  without 
  interbasal 
  muscle. 
  Length 
  of 
  full-grown 
  specimen 
  110 
  

   mm. 
  ; 
  proboscis 
  30 
  mm. 
  ; 
  diameter 
  20 
  mm. 
  A 
  specimen 
  collected 
  at 
  

   Cabrillo 
  Beach, 
  San 
  Pedro, 
  Cahf., 
  is 
  95 
  mm. 
  long; 
  proboscis 
  93 
  mm. 
  

  

  Description. 
  — 
  Longitudinal 
  muscle 
  bands 
  8, 
  well 
  developed, 
  broader 
  

   than 
  the 
  intervals 
  between, 
  rather 
  iridescent 
  and 
  situated 
  as 
  a 
  mid- 
  

   dorsal, 
  midventral, 
  and 
  (twice) 
  three 
  laterals. 
  These 
  fuse 
  into 
  a 
  

   continuous 
  sheath 
  on 
  the 
  posterior 
  part 
  of 
  body, 
  equal 
  to 
  about 
  one- 
  

   third 
  body 
  length 
  of 
  expanded 
  specimens 
  and 
  less 
  of 
  contracted 
  ones. 
  

   Anteriorly 
  they 
  remain 
  separated 
  to 
  the 
  base 
  of 
  proboscis. 
  The 
  

   innermost 
  or 
  oblique 
  muscles 
  are 
  well 
  developed, 
  and 
  between 
  the 
  

   longitudinal 
  muscle 
  bands 
  they 
  form 
  a 
  consecutive 
  series 
  of 
  oblique 
  

   partitions 
  alternating 
  with 
  narrow 
  compartments. 
  At 
  the 
  bottom 
  

   of 
  these 
  compartments 
  is 
  a 
  thin 
  layer 
  of 
  the 
  longitudinal 
  middle 
  sheet. 
  

   In 
  the 
  posterior 
  region 
  the 
  oblique 
  fascicles 
  become 
  less 
  and 
  less 
  

   distinct 
  as 
  the 
  anal 
  area 
  is 
  approached. 
  In 
  reality 
  the 
  uninterrupted 
  

   layer 
  of 
  longitudinal 
  muscles 
  is 
  covered 
  by 
  a 
  continuous 
  inner 
  layer 
  

   of 
  oblique 
  muscles 
  differentiated 
  into 
  thicker 
  and 
  thinner 
  portions. 
  

   Thus, 
  forward 
  from 
  the 
  anus 
  the 
  gradual 
  differentiation 
  of 
  the 
  separate 
  

   oblique 
  strands 
  can 
  be 
  easily 
  seen. 
  In 
  severely 
  contracted 
  specimens 
  

   this 
  posterior 
  region 
  does 
  not 
  show 
  to 
  advantage. 
  

  

  Anterior 
  nephridia, 
  2 
  pairs, 
  the 
  ducts 
  piercing 
  the 
  midventral 
  

   muscle 
  about 
  midway 
  between 
  its 
  outer 
  margin 
  and 
  the 
  nerve 
  cord. 
  

   The 
  anterior 
  pair 
  is 
  situated 
  a 
  short 
  distance 
  behind 
  the 
  setae 
  (rather 
  

   less 
  than 
  length 
  of 
  seta). 
  The 
  interval 
  between 
  first 
  and 
  second 
  is 
  a 
  

   little 
  more 
  than 
  twdce 
  the 
  distance. 
  They 
  open 
  internally 
  by 
  ciliated 
  

   funnels 
  having 
  very 
  long, 
  coiled, 
  extensible 
  lips. 
  

  

  Anal 
  vesicles 
  2, 
  unbranched, 
  capable 
  of 
  great 
  distension. 
  They 
  open 
  

   on 
  the 
  ventral 
  surface 
  of 
  cloaca. 
  Tiny 
  scattered 
  ciliated 
  funnels 
  

   may 
  be 
  seen 
  on 
  the 
  surface. 
  

  

  Alimentary 
  canal. 
  There 
  are 
  three 
  general 
  regions: 
  (1) 
  An 
  

   anterior 
  division 
  or 
  foregut, 
  in 
  which 
  the 
  longitudinal 
  musculature 
  lies 
  

   outside 
  the 
  circular 
  musculature; 
  (2) 
  an 
  intestine 
  proper, 
  in 
  which 
  this 
  

   order 
  is 
  reversed, 
  characterized 
  by 
  the 
  presence 
  of 
  the 
  ciliated 
  groove 
  

   and 
  along 
  a 
  part 
  of 
  its 
  course 
  by 
  the 
  collateral 
  intestine 
  or 
  siphon; 
  

   and 
  (3) 
  a 
  short 
  rectum, 
  or 
  cloaca, 
  posterior 
  to 
  the 
  coecum. 
  

  

  The 
  foregut 
  consists 
  of 
  the 
  pharynx, 
  esophagus, 
  gizzard, 
  and 
  stom- 
  

   ach, 
  and 
  the 
  junction 
  with 
  intestine 
  coincides 
  \vith 
  the 
  position 
  of 
  the 
  

   ring 
  blood 
  vessel. 
  The 
  pharynx 
  has 
  a 
  tough 
  wall, 
  rather 
  iridescent 
  

   with 
  wavy 
  longitudinal 
  lines; 
  the 
  esophagus 
  is 
  thin-walled 
  and 
  con- 
  

   voluted, 
  while 
  the 
  gizzard 
  and 
  stomach, 
  both 
  brief, 
  can 
  be 
  differen- 
  

  

  