﻿IREDALE 
  : 
  NOTES 
  ON 
  POLYPLACOPHOEA. 
  99 
  

  

  ? 
  C. 
  petholatus. 
  Sow., 
  Mag. 
  K^t. 
  Hist., 
  n.s., 
  1840, 
  vol. 
  iv, 
  p. 
  289; 
  

  

  \^x. 
  porphyrius, 
  Sow., 
  loc. 
  cit. 
  

   Clmtopleura 
  conspersa, 
  Ad. 
  & 
  Ang., 
  P.Z.S., 
  1864, 
  p. 
  193; 
  P.Z.S., 
  

  

  . 
  1865, 
  p. 
  187. 
  

   Plaxiphora 
  albida, 
  Blain. 
  : 
  Thiele, 
  Zool. 
  Chun, 
  1909, 
  Heft 
  Ivi, 
  p. 
  24, 
  

  

  pi. 
  iii, 
  figs. 
  22, 
  23. 
  

   P. 
  Tasmanica, 
  Blain. 
  : 
  Thiele, 
  loc. 
  cit., 
  p. 
  25, 
  pi. 
  iii, 
  figs. 
  24-6, 
  

   P. 
  BednaUi, 
  Blain. 
  : 
  Thiele, 
  loc. 
  cit., 
  p. 
  25, 
  pi. 
  iii, 
  figs. 
  27-30. 
  

  

  Variously 
  alluded 
  to 
  ix.% 
  petholata, 
  Sow., 
  and 
  glauca, 
  Q,. 
  & 
  Gr. 
  I 
  have 
  

   seen 
  this 
  species 
  from 
  JSTew 
  South 
  Wales, 
  Victoria, 
  South 
  Australia, 
  

   and 
  Tasmania. 
  

  

  Plaxiphora 
  PiETELiANA, 
  Thiele. 
  

   Plaxiphora 
  PtBteliana, 
  Thiele, 
  Zool. 
  Chun, 
  1909, 
  Heft 
  Ivi, 
  p. 
  26, 
  pi. 
  iii, 
  

   tigs. 
  34-6. 
  

   This 
  species 
  I 
  have 
  only 
  as 
  yet 
  seen 
  from 
  Port 
  Jackson, 
  New 
  South 
  

   Wales. 
  

  

  PXiAXIPHOEA 
  MaTTHEWSI, 
  U.Sp. 
  

  

  Plaxiphora 
  connpersa 
  [non 
  Ad. 
  & 
  Aug.), 
  Bednall, 
  Proc. 
  Malac. 
  Soc, 
  

   1897, 
  vol. 
  ii, 
  p. 
  154. 
  

  

  Shell 
  small, 
  keeled, 
  elevated, 
  elongate 
  oval, 
  side 
  slopes 
  straight. 
  

   The 
  shells 
  are 
  usually 
  covered 
  with 
  algae, 
  but 
  the 
  ground 
  colour 
  

   can 
  be 
  discerned 
  as 
  yellowish 
  white, 
  with 
  longitudinal 
  brownish 
  

   markings. 
  The 
  anterior 
  valve 
  is 
  eight-ribbed 
  ; 
  the 
  ribs 
  are 
  strong 
  and 
  

   crenulate 
  the 
  margin 
  of 
  the 
  tegmentum. 
  It 
  is 
  broad, 
  very 
  elevated, 
  

   with 
  the 
  apex 
  acute, 
  and 
  slightly 
  recurved. 
  The 
  insertion 
  plate 
  is 
  

   very 
  short, 
  thick, 
  cut 
  into 
  by 
  eight 
  evenly 
  spaced 
  grooved 
  teeth, 
  

   thickened 
  at 
  the 
  edges 
  of 
  the 
  slits, 
  convex 
  internally. 
  Externally, 
  

   between 
  the 
  ribs, 
  angularly 
  corrugated. 
  The 
  median 
  valves 
  have 
  the 
  

   lateral 
  areas 
  indicated 
  by 
  a 
  strong 
  elevated 
  rib 
  which 
  is 
  nodose 
  in 
  

   young 
  specimens. 
  The 
  posterior 
  margin 
  of 
  the 
  median 
  valves 
  is 
  raised 
  

   by 
  a 
  similar 
  strong 
  rib 
  ; 
  between 
  these 
  two 
  the 
  slight 
  sculpture 
  is 
  

   wrinkle 
  V-shaped. 
  The 
  pleural 
  areas 
  are 
  corrugately 
  sculptured 
  

   towards 
  the 
  sides, 
  becoming 
  smooth 
  on 
  the 
  median 
  areas. 
  The 
  sutural 
  

   laminae 
  broad, 
  short, 
  with 
  the 
  sinus 
  narrow 
  ; 
  highest 
  about 
  midway 
  

   between 
  sinus 
  and 
  edge, 
  but 
  in 
  the 
  fifth 
  valve 
  scarcely 
  appreciable. 
  

   The 
  insertion 
  plates 
  are 
  as 
  in 
  anterior 
  valve, 
  very 
  short, 
  thick, 
  one 
  

   slit 
  agreeing 
  with 
  the 
  lateral 
  rib. 
  The 
  posterior 
  valve 
  is 
  broad, 
  the 
  

   tegmentum 
  narrow 
  from 
  sinus 
  to 
  mucro, 
  which 
  is 
  terminal, 
  acute, 
  and 
  

   elevated. 
  The 
  lateral 
  area 
  consists 
  of 
  a 
  crescentic 
  raised 
  rib, 
  in 
  front 
  

   of 
  which 
  is 
  a 
  concave 
  portion, 
  with 
  an 
  anterior 
  elevation. 
  The 
  

   insertion 
  plate 
  is 
  represented 
  by 
  a 
  thick 
  semicircular, 
  slightly 
  sinuated 
  

   callus. 
  The 
  sutural 
  laminae 
  are 
  broad, 
  short, 
  and 
  almost 
  straight. 
  

   The 
  internal 
  coloration 
  is 
  white 
  with 
  the 
  faintest 
  bluish 
  tinge. 
  

  

  In 
  the 
  dried 
  specimens 
  I 
  have, 
  the 
  girdle 
  is 
  leathery, 
  with 
  hairs 
  

   disposed 
  in 
  bundles 
  at 
  the 
  sutures. 
  I 
  anticipate 
  this 
  description 
  of 
  

   the 
  girdle 
  will 
  need 
  emendation 
  upon 
  examination 
  of 
  fresh 
  shells. 
  

   It 
  shows 
  a 
  posterior 
  sinuation. 
  Length 
  of 
  type, 
  22 
  mm. 
  ; 
  breadth, 
  

   13 
  mm. 
  

  

  