﻿806 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  vol.xx. 
  

  

  angular 
  notch; 
  "while 
  the 
  tooth 
  itself 
  is 
  relatively 
  smaller, 
  shorter, 
  

   less 
  ijromiueut, 
  aud 
  more 
  distinctly 
  triangular 
  in 
  form. 
  

  

  CUSPIDARIA 
  SUBTORTA 
  (Sars). 
  

   (Plates 
  LXXIII, 
  fig. 
  1; 
  LXXIV, 
  figs. 
  4, 
  5.) 
  

  

  Nea'ra 
  suhtorta 
  .Sars, 
  G. 
  O., 
  Mollusca 
  Reg. 
  Arcticae 
  Norvegiae, 
  p. 
  87, 
  pi. 
  6, 
  figs. 
  

   6, 
  a-c, 
  1878. 
  — 
  Jeffreys, 
  Ami. 
  Mag. 
  Nat. 
  Hist., 
  p. 
  234, 
  September, 
  1877; 
  I'roc. 
  

   Zo()l. 
  Soc, 
  Loudon, 
  p. 
  937, 
  November, 
  1881. 
  — 
  Smith, 
  E. 
  A., 
  Report 
  Yoy. 
  Chal- 
  

   lenijcr, 
  Zo()l. 
  Lainellibrancliiata, 
  XIII, 
  p. 
  35, 
  1885. 
  

  

  Shell 
  inequivalve, 
  rather 
  short, 
  relatively 
  high, 
  much 
  swollen 
  in 
  the 
  

   middle, 
  with 
  tumid 
  umbos 
  and 
  a 
  short, 
  tapered, 
  somewhat 
  upturned 
  

   rostrum. 
  The 
  anterior 
  portion 
  is 
  broadlj^ 
  rounded, 
  the 
  margin 
  forming 
  

   nearly 
  a 
  semicircle; 
  the 
  antero-dorsal 
  margin 
  is 
  strongly 
  convex 
  and 
  

   slightly 
  excurved; 
  the 
  ventral 
  margin 
  is 
  evenly 
  rounded, 
  except 
  at 
  

   the 
  base 
  of 
  the 
  rostrum 
  Avhere 
  it 
  is 
  distinctly 
  incurved, 
  especially 
  in 
  

   the 
  right 
  valve; 
  the 
  postero-dorsal 
  margin 
  is 
  very 
  strongly 
  concave 
  in 
  

   the 
  left 
  valve 
  and 
  less 
  so 
  in 
  the 
  right. 
  The 
  rostrum 
  is 
  separated 
  from 
  

   the 
  body 
  of 
  the 
  shell 
  by 
  a 
  sinuous 
  depression 
  and 
  has 
  a 
  poorly 
  defined 
  

   diagonal 
  ridge 
  ; 
  it 
  is 
  a 
  little 
  bent 
  to 
  the 
  left 
  and, 
  when 
  viewed 
  from 
  above, 
  

   appears 
  slightly 
  twisted. 
  The 
  surface 
  of 
  the 
  shell 
  is 
  nearly 
  smooth, 
  

   but 
  shows 
  distinct 
  lines 
  of 
  growth 
  anteriorly, 
  and 
  especially 
  on 
  the 
  

   superior 
  part 
  of 
  the 
  rostrum; 
  the 
  epidermis 
  is 
  very 
  thin, 
  yellowish 
  

   white, 
  more 
  or 
  less 
  wrinkled 
  on 
  the 
  rostrum 
  ; 
  the 
  hinge-margin 
  is 
  rather 
  

   strong; 
  the 
  lateral 
  tooth 
  in 
  the 
  right 
  valve 
  is 
  large, 
  rather 
  elongated, 
  

   rather 
  prominent, 
  obtusely 
  triangular, 
  aud 
  not 
  separated 
  from 
  the 
  very 
  

   small, 
  narrow, 
  oblique, 
  sunken 
  cartilage-plate 
  by 
  a 
  notch; 
  iu 
  the 
  left 
  

   valve 
  there 
  is 
  a 
  small, 
  short, 
  prominent 
  tooth 
  arising 
  from 
  the 
  poste- 
  

   rior 
  margin 
  of 
  the 
  cartilage-plate 
  and 
  separated 
  from 
  the 
  posterior 
  

   hinge-margin 
  by 
  a 
  distinct 
  angular 
  notch. 
  

  

  Length, 
  8 
  mm.; 
  height, 
  6 
  mm.; 
  breadth, 
  about 
  5 
  mm. 
  

  

  One 
  live 
  specimen 
  (Ko. 
  52545), 
  station 
  2499, 
  N. 
  lat. 
  44° 
  4G' 
  30", 
  W. 
  

   long. 
  59° 
  55' 
  45", 
  iu 
  130 
  fathoms, 
  1885. 
  

  

  This 
  species 
  appears 
  to 
  be 
  identical 
  with 
  the 
  European 
  snhtorta. 
  It 
  

   differs 
  from 
  all 
  of 
  our 
  other 
  species 
  in 
  having 
  a 
  distinct 
  tooth-like 
  

   tubercle 
  behind 
  the 
  cartilage-plate 
  in 
  the 
  left 
  valve. 
  The 
  inequality 
  

   of 
  the 
  valves 
  and 
  the 
  twisted 
  rostrum 
  give 
  the 
  shell 
  a 
  peculiar 
  aspect. 
  

  

  CARDIOMYA 
  ABYSSICOLA, 
  new 
  species. 
  

  

  (Plates 
  LXXIII, 
  lig. 
  4; 
  LXXIV, 
  fig. 
  1; 
  LXXVII, 
  fig. 
  9.) 
  

  

  Shell 
  rather 
  large, 
  swollen, 
  with 
  tumid 
  umbos 
  ; 
  outline 
  elongate-ovate, 
  

   with 
  a 
  narrow, 
  rather 
  elongated, 
  tapered, 
  slightly 
  excurved 
  posterior 
  

   rostrum, 
  the 
  tips 
  divergent 
  and 
  gaping; 
  the 
  anterior 
  end 
  is 
  broadly 
  

   round, 
  with 
  the 
  dorsal 
  and 
  ventral 
  margins 
  convex, 
  the 
  latter 
  narrow- 
  

   ing 
  gradually 
  posteriorly 
  with 
  a 
  slight 
  sinus 
  at 
  the 
  base 
  of 
  the 
  rostrum 
  ; 
  

   the 
  postero-dorsal 
  margin 
  is 
  concave, 
  so 
  that 
  the 
  end 
  of 
  the 
  rostrum 
  is 
  

  

  