﻿[37] 
  ANNELIDA 
  CH.ETOPODA. 
  743 
  

  

  Length, 
  7-10 
  mm 
  . 
  

  

  Diameter 
  in 
  front, 
  0.6-0.7 
  mm 
  . 
  

  

  Diameter 
  posterior 
  end, 
  0.2-0.21 
  mm 
  . 
  

  

  Not 
  common; 
  20 
  tathoms; 
  rocks 
  and 
  shells. 
  

  

  COSSURA, 
  n. 
  q. 
  

  

  Head 
  and 
  first 
  two 
  segments 
  without 
  appendages 
  (fig. 
  105). 
  Fourth 
  

   segment 
  with 
  single 
  median 
  cirrus; 
  no 
  lateral 
  cirri 
  (branchiae). 
  Capil- 
  

   lary 
  setae, 
  dorsal 
  and 
  ventral 
  from 
  the 
  third 
  segment. 
  Anal 
  segment, 
  

   with 
  three 
  anal 
  cirri. 
  

  

  COSSURA 
  LONGOCIRRATA, 
  n. 
  sp. 
  

   (Pl. 
  VIII, 
  Figs. 
  105-107.) 
  

  

  Head 
  conical 
  (fig. 
  105) 
  ; 
  first 
  segment 
  a 
  little 
  shorter 
  than 
  the 
  second 
  ; 
  

   second 
  as 
  long 
  as 
  the 
  third. 
  The 
  median 
  cirrus 
  of 
  the 
  fourth 
  segment 
  

   is 
  very 
  long, 
  reaching 
  back 
  to 
  the 
  twenty-fifth 
  segment. 
  It 
  increases 
  

   regularly 
  in 
  diameter 
  along 
  the 
  first 
  fourth 
  of 
  its 
  length, 
  then 
  tapers 
  

   very 
  gradually 
  to 
  the 
  end. 
  Along 
  the 
  anterior 
  part 
  of 
  this 
  cirrus 
  well- 
  

   defined 
  and 
  regular 
  constrictions 
  exist; 
  these 
  also 
  occur 
  along 
  the 
  en- 
  

   tire 
  cirrus, 
  but 
  irregularly. 
  

  

  The 
  bundles 
  of 
  dorsal 
  and 
  ventral 
  setae 
  are 
  close 
  to 
  each 
  other, 
  form- 
  

   ing 
  a 
  nearly 
  continuous 
  series 
  ; 
  the 
  setae 
  are 
  short 
  in 
  front 
  (fig. 
  105), 
  on 
  

   the 
  middle 
  segments 
  nearly 
  as 
  long 
  as 
  the 
  width 
  of 
  the 
  body, 
  while 
  on 
  

   the 
  posterior 
  segments 
  the3 
  r 
  again 
  shorten 
  somewhat. 
  

  

  In 
  living 
  specimens 
  the 
  lines 
  of 
  segmentation 
  are 
  very 
  faint 
  along 
  the 
  

   anterior 
  third 
  ; 
  farther 
  back 
  very 
  deep, 
  giving 
  to 
  the 
  body 
  a 
  moniliform 
  

   appearance 
  ; 
  on 
  the 
  extreme 
  posterior 
  segments 
  not 
  so 
  well 
  defined. 
  

  

  Only 
  one 
  specimen 
  with 
  anal 
  segment 
  and 
  cirri 
  was 
  taken, 
  and 
  in 
  

   this 
  the 
  anal 
  segment 
  was 
  somewhat 
  injured. 
  It 
  appeared 
  to 
  be 
  trun- 
  

   cated 
  from 
  above 
  downward 
  ; 
  it 
  bears 
  three 
  delicate 
  anal 
  cirri, 
  as 
  long 
  

   as 
  the 
  last 
  8-10 
  segments. 
  

  

  Length, 
  6 
  mm 
  . 
  

  

  Diameter, 
  0.6-0.8 
  mm 
  . 
  

  

  Number 
  of 
  segments, 
  50-70. 
  

  

  Mud 
  and 
  sandy 
  mud 
  ; 
  6-12 
  fathoms. 
  

  

  LEDON, 
  n. 
  g. 
  

  

  We 
  found 
  two 
  specimens, 
  both 
  somewhat 
  injured, 
  which 
  seemed 
  to 
  

   represent 
  a 
  new 
  genus, 
  allied 
  to 
  Acrocirrus 
  and 
  Macrochceta, 
  but 
  not 
  

   agreeing 
  perfectly 
  with 
  either. 
  It 
  differs 
  from 
  Macrochceta 
  Grube, 
  as 
  

   described 
  and 
  figured 
  by 
  Langerhans, 
  in 
  having 
  cirri 
  (? 
  branchiae) 
  on 
  

   the 
  buccal 
  segment 
  ; 
  and 
  from 
  Acrocirrus 
  in 
  having 
  (apparently) 
  but 
  

   one 
  pair 
  of 
  appendages 
  on 
  the 
  buccal 
  segment, 
  instead 
  of 
  two 
  ; 
  and 
  (cer- 
  

  

  