﻿NO. 
  1139. 
  DEKP-WATEB 
  MOLLUSCA—VERRILL 
  AND 
  BUSH. 
  817 
  

  

  Family 
  LYONSIELLID^E. 
  

  

  LYONSIELLA 
  SUBQUADRATA 
  (Jeffreys.) 
  

  

  (Plate 
  LXXXVII, 
  tig. 
  3.) 
  

  

  Pecchiolia 
  sithqiiadrala 
  Jeffreys, 
  Proc. 
  Zoiil. 
  Soc. 
  Loiulon, 
  p. 
  932, 
  pi. 
  lxx, 
  lig. 
  3, 
  

   November, 
  1881.— 
  Not 
  Dall, 
  Bull. 
  Mus. 
  Comp. 
  Zool., 
  XII, 
  p. 
  272, 
  1X86. 
  

  

  Our 
  specimen 
  seems 
  to 
  agree 
  in 
  every 
  respect, 
  except 
  size, 
  with 
  the 
  

   original 
  description 
  and 
  iigure 
  as 
  given 
  by 
  Jeffreys, 
  ours 
  being 
  consid- 
  

   erably 
  larger. 
  

  

  The 
  umbo 
  is 
  prominent 
  and 
  the 
  beak 
  is 
  curved 
  strongly 
  forward, 
  pro- 
  

   ducing 
  a 
  deep 
  lunular 
  area 
  which 
  is 
  defined 
  neither 
  by 
  a 
  groove 
  nor 
  

   a 
  ridge. 
  The 
  surface 
  is 
  everywhere 
  covered 
  with 
  small 
  but 
  prominent 
  

   granules 
  which 
  are 
  numerous, 
  pretty 
  evenly 
  spaced, 
  and 
  arranged 
  

   somewhat 
  distinctly 
  in 
  radiating 
  rows 
  which, 
  under 
  the 
  microscope, 
  are 
  

   <lefined 
  by 
  slight 
  radial 
  ridges 
  uniting 
  those 
  of 
  the 
  same 
  row. 
  The 
  

   granulations 
  are 
  easily 
  visible 
  with 
  slight 
  enlargement. 
  Under 
  the 
  

   compound 
  microscope 
  they 
  have 
  the 
  form 
  of 
  elevated, 
  acute 
  cones 
  and 
  

   blunt 
  tubercles, 
  their 
  height 
  usually 
  greater 
  than 
  their 
  diameter, 
  except 
  

   on 
  the 
  umbo, 
  where 
  they 
  are 
  low 
  and 
  rounded. 
  Internally 
  the 
  surface 
  

   is 
  everywhere 
  marked 
  with 
  small, 
  deep 
  pits 
  looking 
  like 
  punctures 
  

   made 
  by 
  a 
  fine 
  needle, 
  and 
  corresponding 
  to 
  the 
  external 
  granules. 
  

   The 
  hinge 
  margin 
  is 
  thickened 
  and 
  entirely 
  edentulous, 
  as 
  described 
  by 
  

   Jeflreys, 
  Posterior 
  to 
  the 
  beak 
  there 
  is 
  a 
  distinct 
  groove 
  in 
  the 
  thick- 
  

   ness 
  of 
  the 
  margin 
  for 
  the 
  reception 
  of 
  a 
  ligament. 
  Beneath 
  the 
  beak 
  

   there 
  is 
  a 
  slight, 
  oblique, 
  marginal 
  notch 
  or 
  slit 
  for 
  the 
  reception 
  of 
  the 
  

   resilium, 
  running 
  back 
  within 
  and 
  underneath 
  the 
  dorsal 
  margin, 
  so 
  

   that 
  it 
  is 
  scarcely 
  visible 
  in 
  a 
  direct 
  front 
  view. 
  

  

  This 
  shell 
  appears 
  to 
  be 
  identical 
  with 
  the 
  species 
  originally 
  described 
  

   and 
  figured 
  by 
  Jeffreys 
  under 
  the 
  name 
  of 
  Pecchiolia 
  suhquadrata. 
  

   Mr. 
  Dall 
  has 
  evidently 
  found 
  an 
  entirely 
  different 
  species 
  in 
  the 
  Jef- 
  

   frey's 
  collection 
  under 
  this 
  name, 
  which 
  he 
  has 
  referred 
  to 
  the 
  genus 
  

   Callocardia 
  and 
  subgenus 
  Vesicomya, 
  belonging 
  to 
  an 
  entirely 
  different 
  

   family 
  from 
  our 
  shell. 
  In 
  order 
  to 
  avoid 
  confusion 
  the 
  shell 
  examined 
  

   and 
  described 
  by 
  Mr. 
  Dall 
  should 
  receive 
  a 
  distinct 
  specific 
  name; 
  we 
  

   thereibre 
  propose 
  Callocardia 
  ( 
  Vesicomya) 
  dalli. 
  Mr. 
  Dall 
  states 
  that 
  

   "the 
  sparsely 
  set, 
  microscopic 
  tubercles 
  can 
  only 
  be 
  observed 
  with 
  a 
  

   niagnitior; 
  to 
  the 
  eye 
  the 
  surfac-e 
  looks 
  shining 
  and 
  smooth," 
  which 
  

   shows 
  the 
  surface 
  to 
  be 
  quite 
  different 
  from 
  that 
  of 
  our 
  shell. 
  In 
  his 
  

   shell 
  there 
  are 
  also 
  two 
  cardinal 
  teeth 
  in 
  each 
  valve. 
  

  

  One 
  valve 
  (Xo. 
  78800), 
  station 
  2711, 
  N. 
  lat. 
  38° 
  22', 
  W. 
  long. 
  70° 
  17' 
  

   30", 
  in 
  1,825 
  fathoms, 
  1886. 
  

  

  North 
  of 
  the 
  Hebrides, 
  in 
  542 
  fathoms; 
  and 
  off 
  Cape 
  Mondego 
  in 
  

   Vigo 
  Bay, 
  in 
  740 
  to 
  1,095 
  fathoms. 
  ^'■Porcupine 
  Expedition, 
  1869-70." 
  — 
  

   Jeffreys. 
  

  

  Proc. 
  N. 
  M. 
  vol. 
  XX 
  52 
  

  

  