﻿a 
  new 
  Amphipod 
  Species. 
  511 
  

  

  Pleon-segments 
  1 
  and 
  2, 
  bind 
  margins 
  straight, 
  postero- 
  

   lateral 
  angles 
  obtuse. 
  Pleon-segment 
  3 
  is 
  the 
  most 
  easily- 
  

   observed 
  distinguishing 
  character 
  of 
  the 
  species; 
  in 
  longipes 
  

   the 
  posterior 
  lobe 
  is 
  acutely 
  upturned, 
  rounding 
  gradually 
  

   below 
  into 
  the 
  interior 
  margin, 
  while 
  in 
  alleni, 
  in 
  all 
  stages 
  

   of 
  growth, 
  the 
  lobe 
  is 
  acutely 
  produced 
  below 
  as 
  well 
  as 
  

   above, 
  the 
  margin 
  between 
  the 
  points 
  being 
  deeply 
  concave 
  

   (% 
  2). 
  

  

  Antennce. 
  — 
  Superior 
  antenna 
  : 
  peduncle 
  as 
  in 
  longipes 
  ; 
  

   flaaella 
  longer 
  in 
  proportion 
  ; 
  primary 
  flagellum 
  in 
  the 
  large 
  

   female 
  considerably 
  more 
  than 
  twice 
  the 
  length 
  of 
  the 
  

   peduncle, 
  18-jointed 
  ; 
  accessory 
  flagellum 
  nearly 
  one-thiid 
  

   the 
  length 
  of 
  the 
  primary, 
  6-jointed. 
  The 
  largest 
  male 
  in 
  

   Mr. 
  Tattersalfs 
  collection 
  had 
  22 
  joints 
  in 
  the 
  primary, 
  6 
  in 
  

   the 
  accessory. 
  

  

  Inferior 
  antenna 
  shorter 
  than 
  the 
  superior 
  in 
  the 
  female 
  ; 
  

   flagellum 
  15-jointed. 
  In 
  the 
  male 
  the 
  flagellum 
  is 
  filiform, 
  

   62 
  joints 
  in 
  the 
  largest 
  specimen, 
  46 
  in 
  the 
  smallest. 
  

  

  Ural 
  parts. 
  — 
  Lower 
  lip 
  much 
  as 
  figured 
  by 
  Sars 
  for 
  longipes, 
  

   densely 
  covered 
  with 
  fine 
  hairs, 
  as 
  is 
  also 
  the 
  upper 
  lip. 
  

  

  Mandibles 
  (tigs. 
  3 
  and 
  4) 
  much 
  as 
  in 
  the 
  type 
  species, 
  but 
  

   distinguished 
  from 
  it 
  by 
  the 
  different 
  proportions 
  of 
  the 
  joints 
  

   of 
  the 
  palp. 
  Cutting 
  -plates 
  large, 
  rounded, 
  with 
  a 
  small 
  

   recurved 
  tooth 
  above. 
  The 
  left 
  mandible 
  (fig. 
  3) 
  has 
  a 
  very 
  

   small 
  accessory 
  plate, 
  the 
  margin 
  of 
  which 
  is 
  divided 
  into 
  

   three 
  rounded 
  teeth. 
  Spine-row 
  with 
  three 
  spines. 
  Molar 
  

   large, 
  prominent 
  ; 
  crown 
  reniform 
  in 
  shape, 
  transversely 
  

   ridged. 
  The 
  palp 
  is 
  very 
  long 
  and 
  slender, 
  the 
  second 
  joint 
  

   longer 
  in 
  proportion 
  than 
  in 
  longipes, 
  twice 
  the 
  length 
  of 
  the 
  

   third, 
  with 
  a 
  row 
  of 
  graduated 
  setiiorm 
  spines 
  crossing 
  its 
  

   distal 
  end 
  diagonally 
  ; 
  third 
  joint 
  narrow, 
  tapering 
  to 
  the 
  tip, 
  

   with 
  a 
  row 
  of 
  serrate 
  spines 
  on 
  the 
  inner 
  margin, 
  and 
  an 
  

   apical 
  cluster 
  of 
  four 
  longer 
  ones 
  setting 
  out 
  at 
  a 
  different 
  

   angle. 
  

  

  Maxilla 
  1 
  (fig. 
  5). 
  — 
  Inner 
  plate 
  tipped 
  with 
  2 
  plumose 
  

   setae; 
  outer 
  plate 
  large, 
  apex 
  obliquely 
  truncate, 
  with 
  11 
  

   strong, 
  flat, 
  dentate 
  spines, 
  10 
  of 
  which 
  are 
  arranged 
  close 
  

   together 
  in 
  two 
  lows, 
  the 
  remaining 
  one 
  being 
  inset 
  lower 
  

   down 
  on 
  the 
  inner 
  margin. 
  Palp 
  large 
  and 
  broad 
  ; 
  apical 
  

   margin 
  rounded 
  and 
  beset 
  with 
  7 
  small 
  stout 
  teeth 
  and 
  1 
  

   short 
  spine. 
  

  

  Maxilla 
  2 
  as 
  in 
  longipes. 
  

  

  Maxillipeds 
  (fig. 
  6). 
  — 
  Inner 
  plate 
  : 
  apex 
  truncate, 
  with 
  3 
  

   short 
  stout 
  teeth 
  ; 
  a 
  row 
  of 
  plumose 
  seta? 
  starting 
  from 
  the 
  

   outer 
  angle 
  runs 
  halfway 
  down 
  the 
  inner 
  margin. 
  Outer 
  

   plate 
  very 
  large, 
  furnished 
  with 
  2 
  stout 
  teeth 
  apical 
  ly 
  and 
  a 
  

  

  