﻿108 
  PEOCEEDINGS 
  OF 
  THE 
  MALACOLOGICAL 
  SOCIETT, 
  

  

  will 
  bear 
  the 
  name 
  urvillei, 
  Rochebrune, 
  given 
  to 
  the 
  shell 
  collected 
  

   by 
  Quoy 
  & 
  Gaimard 
  in 
  King 
  George's 
  Sound, 
  West 
  Australia. 
  

  

  Isehnochiton 
  lineolatus 
  (Blainville). 
  PI. 
  IV, 
  Fi"-. 
  1. 
  

  

  lichnochiton 
  co7ifractus, 
  Pilsbry, 
  1895 
  (not 
  of 
  Reeve, 
  1847), 
  and 
  

   of 
  all 
  recent 
  writers. 
  A 
  good 
  description 
  was 
  published 
  by 
  Pilsbry 
  

   in 
  the 
  Manual, 
  extracted 
  from 
  Carpenter's 
  MS., 
  but 
  no 
  figure 
  has 
  yet 
  

   appeared. 
  We 
  remedy 
  this 
  latter 
  point, 
  but 
  do 
  not 
  give 
  any 
  further 
  

   description, 
  since 
  the 
  shell 
  we 
  figure 
  is 
  well 
  known, 
  and 
  complications 
  

   occur 
  in 
  specimens 
  from 
  southern 
  Tasmania 
  which 
  we 
  have 
  not 
  yet 
  

   completely 
  cleared 
  up. 
  

  

  The 
  typical 
  form 
  is 
  very 
  common 
  in 
  South 
  Australian 
  waters, 
  

   where 
  little 
  variation 
  exists. 
  One 
  of 
  us 
  collected 
  it 
  in 
  the 
  Flinders 
  

   Group, 
  and 
  odd 
  specimens 
  with 
  the 
  same 
  distinctive 
  coloration 
  have 
  

   been 
  taken 
  in 
  southern 
  Tasmania. 
  

  

  "/. 
  contractus" 
  must 
  now 
  be 
  entirely 
  omitted 
  from 
  the 
  New- 
  

   Zealand 
  fauna. 
  

  

  10. 
  IscHNOCHiTON(ANisoRADsrA, 
  n.subg.) 
  MAWLEi, 
  n.sp. 
  PI. 
  IV, 
  Fig. 
  4. 
  

  

  Shell 
  of 
  full 
  size 
  for 
  the 
  genus, 
  elongate 
  elliptical, 
  valves 
  round- 
  

   backed, 
  low, 
  not 
  keeled 
  nor 
  beaked. 
  Colour 
  uniform 
  pale 
  yellow. 
  

   The 
  following 
  description 
  of 
  the 
  sculpture 
  is 
  drawn 
  up 
  from 
  a 
  small 
  

   normal 
  specimen 
  selected 
  as 
  type. 
  

  

  Anterior 
  valve 
  sculptured, 
  with 
  fifty 
  to 
  sixty 
  low 
  radials, 
  which 
  are 
  

   curved, 
  straggling, 
  convergent, 
  and 
  more 
  or 
  less 
  undefined, 
  so 
  that 
  

   scarcely 
  any 
  one 
  can 
  be 
  traced 
  from 
  apex 
  to 
  edge. 
  Median 
  valves 
  

   show 
  the 
  same 
  sculpture 
  on 
  the 
  lateral 
  areas, 
  but 
  more 
  irregular 
  

   development 
  still 
  is 
  here 
  noticeable. 
  The 
  pleural 
  areas 
  are 
  sculptured 
  

   at 
  the 
  sides 
  with 
  irregular 
  longitudinal 
  threads, 
  more 
  or 
  less 
  wavv, 
  

   which 
  become 
  obsolete 
  towards 
  the 
  jugum, 
  the 
  dorsal 
  area 
  being 
  

   covered 
  with 
  fine 
  zigzag 
  scratches. 
  Tail-valve 
  large 
  with 
  mucro 
  

   elevated 
  at 
  about 
  the 
  anterior 
  third, 
  posterior 
  slope 
  straight. 
  Posterior 
  

   area 
  sculptured 
  like 
  the 
  anterior 
  valve, 
  but 
  more 
  roughly, 
  separated 
  

   lozenges 
  commonly 
  occurring 
  ; 
  anterior 
  sculpture 
  like 
  that 
  of 
  pleura 
  

   of 
  median 
  valves. 
  Variation 
  in 
  sculpture 
  is 
  slight, 
  age 
  developing 
  

   more 
  radials 
  on 
  anterior 
  valve 
  and 
  lateral 
  areas 
  of 
  median 
  valves, 
  

   while 
  concentric 
  growth-lines 
  become 
  more 
  prominent 
  and 
  tend 
  to 
  

   form 
  lozenges 
  on 
  these 
  areas, 
  the 
  posterior 
  area 
  of 
  tail-valve 
  generally 
  

   showing 
  this 
  lozenge 
  formation 
  more 
  boldly. 
  Interior 
  coloration 
  pure 
  

   white. 
  In 
  young 
  shells 
  both 
  the 
  tegmentum 
  and 
  articulamentum 
  are 
  

   brittle. 
  The 
  sutural 
  laminae 
  and 
  teeth 
  are 
  typically 
  Ischnoid, 
  but 
  

   the 
  latter 
  are 
  very 
  short. 
  In 
  the 
  anterior 
  valve 
  twenty 
  slits 
  were 
  

   counted 
  in 
  a 
  senile 
  shell, 
  twenty-five 
  in 
  a 
  young 
  one, 
  the 
  teeth 
  

   irregular 
  in 
  shape. 
  In 
  the 
  posterior 
  valve 
  eighteen 
  irregular 
  slits 
  

   were 
  noted 
  in 
  the 
  senile 
  shell, 
  eighteen 
  regular 
  ones 
  in 
  the 
  young 
  

   one. 
  In 
  the 
  median 
  valves 
  the 
  sinus 
  is 
  broad, 
  about 
  one-third 
  the 
  

   breadth 
  of 
  the 
  valve, 
  the 
  sutural 
  laminae 
  are 
  long 
  and 
  evenly 
  shaped 
  ; 
  

   the 
  lateral 
  teeth 
  are 
  very 
  short, 
  exceeded 
  by 
  the 
  tegmentum^ 
  and 
  two, 
  

   three, 
  or 
  four 
  slits 
  occur. 
  The 
  external 
  appearance 
  of 
  the 
  shell 
  is 
  

   distinctive, 
  but 
  detail 
  figures 
  of 
  the 
  valves 
  will 
  be 
  given 
  later. 
  Girdle 
  

  

  