﻿220 
  PKOCKEDINGS 
  OF 
  THK 
  MALACOLOGICAL 
  SOCIETT. 
  

  

  I 
  had 
  suspected 
  this 
  to 
  be 
  the 
  case 
  in 
  1908 
  from 
  an 
  inspection 
  of 
  

   M. 
  Cossmann's 
  figure, 
  but 
  did 
  not 
  feel 
  justified 
  in 
  saying 
  so 
  because 
  

   I 
  had 
  not 
  then 
  been 
  able 
  to 
  examine 
  any 
  specimens. 
  Early 
  in 
  the 
  

   present 
  year 
  M. 
  Cossmann 
  was 
  kind 
  enough 
  to 
  .send 
  me 
  excellent 
  

   specimens 
  of 
  both 
  valves 
  of 
  this 
  rare 
  and 
  delicate 
  shell, 
  asking 
  me 
  at 
  

   the 
  same 
  time 
  to 
  give 
  him 
  my 
  opinion 
  of 
  its 
  affinities. 
  

  

  On 
  examining 
  them 
  I 
  found 
  that 
  the 
  hinge 
  closely 
  resembles 
  that 
  

   of 
  L^icinopsis, 
  having 
  three 
  cardinal 
  teeth 
  in 
  the 
  left 
  valve, 
  the 
  

   posterior 
  one 
  long 
  and 
  narrow, 
  the 
  median 
  triangular 
  and 
  bifid, 
  and 
  

   the 
  anterior 
  short, 
  prominent, 
  and 
  parallel 
  to 
  the 
  anterior 
  face 
  of 
  the 
  

   median 
  so 
  that 
  the 
  teeth 
  are 
  divergent. 
  In 
  the 
  right 
  valve 
  there 
  are 
  

   only 
  posterior 
  and 
  median 
  teeth, 
  the 
  anterior 
  being 
  absent, 
  and 
  the 
  

   front 
  part 
  of 
  the 
  hinge-plate 
  is 
  concave 
  as 
  in 
  Lueinopsis 
  and 
  in 
  

   dementia. 
  The 
  hinge, 
  in 
  fact, 
  only 
  differs 
  from 
  that 
  of 
  Lueinopsis 
  in 
  

   being 
  more 
  oblique 
  owing 
  to 
  the 
  shape 
  of 
  the 
  shell. 
  

  

  The 
  shell 
  is 
  small, 
  thin, 
  quite 
  smooth 
  and 
  elongate-oval 
  in 
  shape, 
  

   like 
  so 
  many 
  species 
  of 
  Tapes. 
  There 
  is 
  no 
  lunule 
  nor 
  escutcheon, 
  

   and 
  the 
  ligament 
  appears 
  to 
  have 
  been 
  short 
  and 
  entirely 
  external. 
  

   The 
  pallial 
  sinus 
  is 
  small 
  and 
  shallow, 
  the 
  pallial 
  line 
  being 
  merely 
  

   bent 
  inwards 
  posteriorly, 
  so 
  that 
  the 
  siphons 
  of 
  the 
  animal 
  must 
  have 
  

   been 
  short. 
  On 
  the 
  whole, 
  therefore, 
  though 
  closely 
  allied 
  to 
  

   Liicinopsis, 
  it 
  must 
  be 
  regarded 
  as 
  sufficiently 
  distinct 
  from 
  the 
  type 
  

   to 
  be 
  considered 
  as 
  a 
  sub-genus, 
  if 
  not 
  a 
  separate 
  genus. 
  

  

  CyclineUa. 
  — 
  So 
  far 
  as 
  I 
  can 
  learn 
  only 
  one 
  species 
  of 
  true 
  Lueinopsis 
  

   is 
  known, 
  the 
  L. 
  undata 
  which 
  inhabits 
  the 
  seas 
  of 
  Western 
  Europe, 
  

   ranging 
  from 
  Norway 
  to 
  the 
  shores 
  of 
  Morocco, 
  and 
  from 
  the 
  Straits 
  

   of 
  Gibraltar 
  eastward 
  to 
  Italy. 
  The 
  American 
  species 
  which 
  some 
  

   authors 
  had 
  referred 
  to 
  Lueinopsis, 
  and 
  others 
  to 
  Cyclina, 
  were 
  

   separated 
  by 
  Dr. 
  Dall 
  in 
  1902 
  ^ 
  under 
  the 
  name 
  of 
  CyclineUa, 
  because 
  

   they 
  had 
  three 
  teeth 
  in 
  each 
  valve. 
  

  

  The 
  type 
  of 
  CyclineUa 
  is 
  C. 
  tenuis 
  (Recluz), 
  and 
  though 
  in 
  shape 
  

   it 
  greatly 
  resembles 
  Lueinopsis, 
  it 
  has 
  a 
  stouter 
  shell 
  and 
  a 
  circum- 
  

   scribed, 
  though 
  not 
  impressed, 
  lunule. 
  In 
  the 
  left 
  valve 
  the 
  median 
  

   tooth 
  is 
  thick, 
  but 
  not 
  bifid, 
  and 
  the 
  posterior 
  is 
  curved 
  not 
  straight 
  

   as 
  in 
  Lueinopsis. 
  In 
  the 
  right 
  valve 
  there 
  are 
  also 
  three 
  teeth, 
  the 
  

   posterior 
  long, 
  curved, 
  and 
  bifid, 
  the 
  median 
  thick 
  and 
  triangular, 
  

   the 
  anterior 
  small, 
  narrow, 
  and 
  straight. 
  The 
  pallial 
  sinus 
  is 
  deep 
  

   and 
  ascending, 
  but 
  narrow, 
  and 
  bluntly 
  pointed, 
  so 
  that 
  it 
  differs 
  

   much 
  from 
  the 
  broad 
  and 
  rounded 
  sinus 
  of 
  Lueinopsis. 
  

  

  In 
  all 
  respects 
  both 
  internal 
  and 
  external 
  Cyelinella 
  resembles 
  

   Cyclina 
  much 
  more 
  closely 
  than 
  it 
  does 
  Lueinopsis, 
  the 
  only 
  important 
  

   difference 
  being 
  the 
  radial 
  structure 
  of 
  the 
  shell 
  in 
  Cyclina, 
  which, 
  

   though 
  feebly 
  marked 
  outside, 
  is 
  strong 
  enough 
  to 
  crenulate 
  the 
  inner 
  

   margin 
  of 
  the 
  shell. 
  

  

  On 
  the 
  whole 
  my 
  opinion 
  is 
  that 
  CyclineUa 
  tenuis 
  belongs 
  to 
  the 
  

   Yeneridae, 
  and 
  I 
  shall 
  be 
  surprised 
  if 
  the 
  animal, 
  when 
  properly 
  

   examined 
  from 
  fresh 
  specimens, 
  does 
  not 
  confirm 
  this 
  view. 
  Dr. 
  Dall 
  

   himself 
  regarded 
  it 
  as 
  forming 
  a 
  separate 
  genus 
  from 
  Lueinopsis, 
  and 
  

  

  ' 
  The 
  Nautilus, 
  vol. 
  xvi, 
  p. 
  44. 
  

  

  