﻿No.li.iQ. 
  DEEP-WATER 
  MOLLUSC 
  A— 
  VEERILL 
  AND 
  BUSH. 
  843 
  

  

  loides 
  (Scacchi) 
  audits 
  vm'ieties, 
  grandis 
  YerTill, 
  Freilei 
  J 
  e&reys, 
  septen- 
  

   trionalis 
  Sars, 
  crenulata 
  Yerrill, 
  orhiculata 
  Dal], 
  from 
  off 
  St. 
  Viiiceut, 
  

   uortliwaid. 
  />. 
  (/lucialin 
  (Gray), 
  Arctic 
  America 
  and 
  Europe. 
  B. 
  tmo- 
  

   maid 
  Verrill 
  and 
  Bush, 
  Gulf 
  of 
  Maine. 
  7>. 
  ahyssorum 
  Verrill 
  and 
  Bush, 
  

   off 
  Delaware 
  Bay. 
  B. 
  profuMlicola 
  Verrill, 
  from 
  oft' 
  West 
  Indies, 
  north- 
  

   ward. 
  B. 
  f/lomerula 
  (Dall), 
  B. 
  liohjcyma 
  (Dall), 
  B. 
  culehrensis 
  (Smith), 
  

   off 
  West 
  Indies. 
  7>. 
  iiKcqui-sculpta 
  (Smith), 
  B. 
  pteroessa 
  (Smith), 
  Atlantic 
  

   and 
  Pacific, 
  i?. 
  twi^ftto 
  (Smith), 
  Pacific. 
  

  

  licniharca 
  aaperida 
  (Dall), 
  and 
  B. 
  sa[/rinata 
  (Dall), 
  are 
  from 
  the 
  West 
  

   Indies, 
  in 
  dee^) 
  water. 
  

  

  BATHYARCA 
  ABYSSORUM, 
  new 
  species. 
  

  

  (Plate 
  LXXVI, 
  fig. 
  9.) 
  

  

  Shell 
  small, 
  short, 
  well-rounded 
  at 
  both 
  ends, 
  s«-ollen, 
  inequilateral, 
  

   slightly 
  oblnjue. 
  with 
  a 
  rather 
  long, 
  straioht 
  hinge-margin. 
  Umbos 
  

   large, 
  swollen, 
  prominent. 
  Beaks 
  prominent 
  and 
  curved 
  strongly 
  for- 
  

   ward, 
  situated 
  considerably 
  in 
  front 
  of 
  the 
  middle. 
  Surface 
  every- 
  

   where 
  covered 
  with 
  nearly 
  equal, 
  delicate, 
  raised, 
  radiating 
  lines 
  and 
  

   small, 
  rather 
  even, 
  raised 
  lines 
  of 
  growth; 
  these 
  together 
  produce 
  a 
  

   finely 
  cancellated 
  surface 
  which, 
  wlien 
  fresh, 
  is 
  covered 
  with 
  a 
  thin 
  

   brownish-yellow 
  epidermis 
  forming 
  small 
  scale-like 
  points 
  at 
  the 
  inter- 
  

   section 
  of 
  the 
  lines; 
  the 
  surface 
  is 
  also 
  marked 
  with 
  slight, 
  irregular, 
  

   concentric 
  waves 
  or 
  undulations. 
  

  

  The 
  anterior 
  margin 
  is 
  shorter 
  than 
  the 
  posterior 
  and 
  forms 
  an 
  

   obtuse, 
  rounded 
  angle 
  at 
  its 
  junction 
  with 
  the 
  hinge-margin; 
  the 
  ven- 
  

   tral 
  margin 
  is 
  obliquely 
  curved, 
  most 
  prominent 
  behind 
  the 
  middle, 
  

   where 
  the 
  curve 
  forms 
  nearly 
  the 
  segment 
  of 
  a 
  circle; 
  posterior 
  margin 
  

   is 
  very 
  broadly 
  rounded 
  and 
  forms 
  a 
  distinct 
  obtuse 
  angle 
  where 
  it 
  

   joins 
  the 
  dorsal 
  margin. 
  The 
  ligamental* 
  area 
  is 
  lanceolate, 
  mod- 
  

   erately 
  large, 
  decidedly 
  wider 
  just 
  in 
  front 
  of 
  the 
  beaks, 
  becoming 
  nar- 
  

   row 
  and 
  pointed 
  posteriorly. 
  The 
  dark 
  ligamental 
  patch 
  is 
  arrow- 
  

   shaped, 
  situated 
  behind 
  the 
  beaks. 
  The 
  hinge-margin 
  is 
  rather 
  wide 
  

   and 
  strong, 
  with 
  a 
  small, 
  central 
  edentulous 
  space, 
  mostly 
  behind 
  the 
  

   beaks. 
  The 
  teeth, 
  which 
  are 
  striated 
  on 
  the 
  sides 
  and 
  crenulated 
  on 
  

   the 
  edge, 
  are 
  eijually 
  and 
  decidedly 
  oblique 
  in 
  the 
  two 
  series; 
  the 
  prox- 
  

   imal 
  ones 
  are 
  small 
  and 
  the 
  others 
  increase 
  in 
  size 
  and 
  obliquity 
  to 
  

   near 
  the 
  end 
  of 
  the 
  series, 
  where 
  one 
  or 
  two 
  of 
  the 
  outermost 
  are 
  

   decidedly 
  smaller 
  and 
  very 
  oblique. 
  In 
  the 
  largest 
  specimen 
  there 
  are 
  

   about 
  six 
  teeth 
  in 
  the 
  anterior 
  and 
  eight 
  in 
  the 
  posterior 
  series. 
  The 
  

   inner 
  surface 
  shows 
  faint 
  radial 
  grooves 
  and 
  ridges, 
  much 
  coarser 
  than 
  

   the 
  external 
  stria^; 
  there 
  is 
  also 
  a 
  fine, 
  impressed 
  line, 
  with 
  a 
  finely 
  

   crenulated 
  edge 
  close 
  to 
  the 
  margin. 
  

  

  Length 
  of 
  the 
  largest 
  sjiecimen, 
  C 
  mm.; 
  height, 
  6. 
  .5 
  mm.; 
  thickness, 
  

   5.5 
  mm.; 
  length 
  of 
  the 
  hinge 
  margin, 
  3.5 
  mm. 
  

  

  Three 
  specimens 
  were 
  found 
  at 
  stations 
  2713 
  and 
  2714, 
  off 
  Delaware 
  

   Bay, 
  in 
  1,825 
  to 
  1,859 
  fathoms, 
  1886. 
  

  

  