﻿320 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  tol. 
  103 
  

  

  branchiae 
  lacking. 
  Without 
  paleae. 
  Tube 
  usually 
  membranous, 
  

   encrusted 
  with 
  sand, 
  debris 
  of 
  shells, 
  algae, 
  etc. 
  

  

  Represented 
  by 
  10 
  genera 
  and 
  11 
  species 
  at 
  Point 
  Barrow. 
  

  

  Key 
  to 
  the 
  genera 
  of 
  TerebeUidae 
  from 
  Point 
  Barrow 
  

  

  1. 
  Uncini 
  in 
  single 
  rows 
  on 
  first 
  6 
  uncinigerous 
  segments, 
  then 
  in 
  2 
  rows 
  (alter- 
  

  

  nating, 
  intercogging 
  or 
  opposite) 
  on 
  certain 
  number 
  of 
  following 
  segments. 
  

   With 
  distinct 
  thoracic 
  ventral 
  shields 
  (single, 
  not 
  paired) 
  . 
  Notosetae 
  begin 
  

   on 
  segment 
  4; 
  uncini 
  begin 
  on 
  segments 
  5 
  or 
  6 
  (setigers 
  2 
  or 
  3), 
  Fused 
  

   prostomium 
  and 
  buccal 
  segment 
  forming 
  a 
  prominent 
  rectangular 
  lower 
  lip, 
  

   a 
  transverse 
  semicircular 
  cephalic 
  ridge 
  (with 
  or 
  without 
  numerous 
  eye-spots 
  

   along 
  basal 
  groove), 
  flared 
  semicircular 
  upper 
  lip, 
  semicircular 
  depressed 
  

   tentacular 
  region 
  between 
  upper 
  lip 
  and 
  cephalic 
  ridge 
  with 
  numerous, 
  

  

  filiform, 
  grooved 
  tentacles 
  (fig. 
  36,/) 
  2 
  

  

  Uncini 
  in 
  single 
  rows 
  only 
  (or 
  with 
  crotchets 
  on 
  thoracic 
  segments) 
  7 
  

  

  2. 
  With 
  1-3 
  pairs 
  branchiae 
  dorsally 
  on 
  segments 
  2-4 
  (fig. 
  36, 
  g, 
  i, 
  k). 
  Uncini 
  

  

  begin 
  on 
  segment 
  5 
  (setiger 
  2) 
  3 
  

  

  Without 
  branchiae. 
  With 
  lateral 
  lobes 
  on 
  anterior 
  segments 
  (fig. 
  37, 
  o) 
  5 
  

  

  3. 
  Notosetae 
  with 
  tips 
  finely 
  denticled 
  (fig. 
  36, 
  h). 
  Cephalic 
  ridge 
  usually 
  

  

  without 
  eye-spots. 
  With 
  lateral 
  lobes 
  on 
  anterior 
  segments 
  (fig. 
  36, 
  g). 
  

  

  Amphitrite 
  (p. 
  321) 
  

   Notosetae 
  with 
  tips 
  smooth. 
  Cephalic 
  ridge 
  usually 
  with 
  eye-spots 
  4 
  

  

  4. 
  Without 
  lateral 
  lobes 
  on 
  anterior 
  segments. 
  Uncini 
  of 
  anterior 
  segments 
  

  

  without 
  long 
  manubrium 
  (fig. 
  36, 
  j). 
  Branchiae 
  2 
  pairs, 
  branched 
  dichoto- 
  

   mously 
  (fig. 
  36, 
  t) 
  Nicolea 
  (p. 
  322) 
  

  

  With 
  large 
  lateral 
  lobes 
  on 
  buccal 
  segment, 
  enclosing 
  prostomium 
  and 
  con- 
  

   nected 
  ventrally 
  (fig. 
  36, 
  k). 
  Uncini 
  of 
  first 
  few 
  segments 
  with 
  long 
  manu- 
  

   brium 
  (fig. 
  36, 
  I). 
  Branchiae 
  1-3 
  pairs, 
  arborescent, 
  with 
  main 
  trunk 
  well 
  

  

  marked 
  Pista 
  (p. 
  323) 
  

  

  6. 
  Uncini 
  begin 
  on 
  segment 
  6 
  (setiger 
  3). 
  Notosetae 
  of 
  2 
  kinds, 
  smooth 
  and 
  

   denticled 
  Proclea 
  (p. 
  325) 
  

  

  Uncini 
  begin 
  on 
  segment 
  5 
  (setiger 
  2). 
  Notosetae 
  with 
  tips 
  smooth 
  6 
  

  

  6. 
  Uncini 
  in 
  single 
  rows 
  on 
  first 
  6 
  uncinigerous 
  segments, 
  in 
  double 
  rows 
  on 
  next 
  

  

  10. 
  Nephridial 
  papillae 
  of 
  segment 
  3 
  not 
  elongated. 
  Notosetae 
  broadly 
  

  

  bilimbate 
  below 
  whipUke 
  tip 
  (fig. 
  37, 
  b) 
  Leaena 
  (p. 
  325) 
  

  

  Uncini 
  in 
  single 
  rows 
  on 
  first 
  6 
  uncinigerous 
  segments, 
  in 
  double 
  rows 
  on 
  next 
  

   8. 
  Nephridial 
  papillae 
  of 
  segment 
  3 
  (anterior 
  to 
  first 
  setiger) 
  elongated. 
  

   Notosetae 
  weakly 
  limbate 
  on 
  one 
  side 
  along 
  most 
  of 
  its 
  length 
  (fig. 
  37, 
  c). 
  

  

  Lanassa 
  (p. 
  326) 
  

  

  7. 
  Uncini 
  all 
  short, 
  avicular 
  (fig. 
  37, 
  d) 
  8 
  

  

  Uncini 
  of 
  2 
  types; 
  thoracic 
  aciculiform, 
  with 
  long 
  manubrium 
  (fig. 
  37, 
  h); 
  

  

  abdominal 
  avicular 
  (fig. 
  37, 
  i). 
  Without 
  ventral 
  shields 
  9 
  

  

  8. 
  Branchiae 
  2-3 
  pairs, 
  cirriform, 
  in 
  transverse 
  rows. 
  Notosetae 
  begin 
  on 
  

  

  segment 
  3, 
  continuing 
  on 
  large 
  number 
  of 
  segments; 
  uncini 
  begin 
  on 
  segment 
  

   5 
  (setiger 
  3). 
  Ventral 
  shields 
  usually 
  slightly 
  distinct. 
  Tentacular 
  lobe 
  

  

  not 
  especially 
  enlarged 
  Thelepus 
  (p. 
  327) 
  

  

  Without 
  branchiae. 
  Notosetae 
  begin 
  on 
  segments 
  2 
  or 
  3; 
  uncini 
  begin 
  on 
  

   variable 
  number 
  of 
  segments, 
  may 
  be 
  absent 
  from 
  thoracic 
  region. 
  With 
  

   ventral 
  shields, 
  first 
  unpaired, 
  rest 
  paired, 
  more 
  or 
  less 
  separated 
  in 
  median 
  

   line 
  (fig. 
  37, 
  /). 
  Tentacular 
  membrane 
  large, 
  trilobed 
  or 
  undulating, 
  

   bearing 
  very 
  numerous 
  tentacles 
  (fig. 
  37, 
  e-/), 
  Polycirrus 
  (p. 
  328) 
  

  

  