﻿JUKES-BROWNE 
  : 
  ON 
  NOMENCLATDKE 
  OF 
  VENERID^. 
  245 
  

  

  the 
  Lamarckian 
  species 
  have 
  been 
  included 
  under 
  one 
  or 
  other 
  of 
  

   the 
  following 
  names, 
  whether 
  these 
  be 
  regarded 
  as 
  genera 
  or 
  sub- 
  

   genera 
  : 
  — 
  

  

  Chione 
  (Megerle, 
  1811). 
  Gomphina 
  (Morch, 
  1853). 
  

  

  Tapes 
  (Megerle, 
  1811). 
  Gircomplialus 
  (Morch, 
  1853). 
  

  

  Mercenaria 
  (Schumacher, 
  1817). 
  Marcia 
  (H. 
  & 
  A. 
  Adams, 
  1857). 
  

  

  ^TCOJ/iftZocaj-dia 
  (Schumacher, 
  1817). 
  Katelysia 
  (Eomer, 
  1857). 
  

  

  Clausina 
  (Brown, 
  1827). 
  Hemitapes 
  (Romer, 
  1857). 
  

  

  Presumably 
  the 
  proper 
  procedure 
  in 
  such 
  a 
  case 
  is 
  to 
  displace 
  one 
  

   of 
  the 
  most 
  recently 
  formed 
  genera 
  by 
  taking 
  its 
  type 
  as 
  the 
  type 
  of 
  

   Venus, 
  provided 
  that 
  the 
  species 
  is 
  otherwise 
  eligible 
  for 
  selection. 
  

   Xow 
  of 
  the 
  species 
  referable 
  to 
  Marcia, 
  Katelysia, 
  and 
  Hemitapes, 
  none 
  

   were 
  known 
  to 
  Linnaeus, 
  neither 
  were 
  the 
  species 
  of 
  Gomphina. 
  

   Again, 
  the 
  type 
  of 
  Clausina 
  ( 
  V. 
  verrucosa) 
  is 
  one 
  of 
  those 
  mentioned 
  

   by 
  Bolten 
  under 
  Ct/iherea, 
  and 
  Circomphalus 
  is 
  only 
  a 
  subgenus 
  of 
  this 
  

   group, 
  by 
  whatever 
  name 
  it 
  may 
  be 
  known. 
  

  

  Chio7ie 
  and 
  Tapes 
  are 
  eliminated 
  as 
  being 
  of 
  earlier 
  date 
  than 
  

   Schumacher's 
  divisions, 
  and 
  I 
  regard 
  Anomalocardia 
  as 
  merely 
  a 
  sub- 
  

   genus 
  of 
  Chione, 
  so 
  that 
  it' 
  its 
  type 
  were 
  chosen 
  to 
  be 
  that 
  of 
  the 
  genus 
  

   Ve?itcs 
  it 
  wouhl 
  elevate 
  a 
  small 
  group 
  to 
  higher 
  rank 
  than 
  a 
  large 
  one. 
  

   The 
  only 
  remaining 
  group 
  is 
  that 
  of 
  jlfercenaria, 
  which 
  is 
  based 
  on 
  the 
  

   V. 
  mercenaria 
  (Linn.), 
  a 
  shell 
  mentioned 
  under 
  Vemcs 
  by 
  Bolten, 
  and 
  

   given 
  by 
  Lamarck 
  as 
  his 
  example 
  of 
  Fenus 
  in 
  1799. 
  The 
  selection 
  of 
  

   this 
  species 
  has 
  the 
  advantage 
  of 
  confirming 
  Dr. 
  Dall's 
  choice 
  which 
  

   was 
  made 
  before 
  tbe 
  promulgation 
  of 
  the 
  strict 
  rule 
  by 
  the 
  Inter- 
  

   national 
  Commission. 
  This 
  is 
  a 
  satisfactory 
  conclusion 
  because 
  further 
  

   alteration 
  is 
  thereby 
  avoided, 
  and 
  Dr. 
  Dall's 
  nomenclature 
  has 
  already 
  

   been 
  accepted 
  by 
  Australian 
  and 
  New 
  Zealand 
  concliologists. 
  

  

  I 
  am 
  not 
  inclined, 
  however, 
  to 
  follow 
  Dr. 
  Dall 
  in 
  restricting 
  the 
  

   genus 
  to 
  the 
  small 
  gi'oup 
  of 
  shells 
  typified 
  by 
  V. 
  mercenaria. 
  I 
  am 
  

   by 
  no 
  means 
  sure 
  that 
  it 
  is 
  generically 
  distinct 
  from 
  Chione, 
  and 
  I 
  am 
  

   quite 
  unable 
  to 
  understand 
  why 
  Dr. 
  Dall 
  separated 
  the 
  ' 
  Venus' 
  

   Bomheyi 
  group 
  from 
  his 
  Venus 
  and 
  Chione 
  groups. 
  He 
  unearthed 
  

   Molina's 
  name 
  of 
  Thaca 
  for 
  V. 
  Bonxbeyi, 
  and 
  made 
  it 
  the 
  type 
  of 
  

   a 
  new 
  subgenus 
  for 
  which 
  he 
  proposed 
  the 
  name 
  of 
  Protothaca 
  ; 
  but 
  

   instead 
  of 
  placing 
  this 
  under 
  Chione 
  he 
  classed 
  it 
  under 
  'Tapes 
  

   (i.e. 
  Paphia). 
  

  

  In 
  reply 
  to 
  in(iuiry 
  as 
  to 
  its 
  affinities 
  with 
  Tapes, 
  the 
  onlj- 
  reason 
  

   he 
  gave 
  me 
  was 
  that 
  he 
  may 
  have 
  been 
  biassed 
  by 
  the 
  fact 
  that 
  the 
  

   North 
  American 
  species 
  had 
  usually 
  been 
  called 
  Tapes 
  \ 
  As 
  these 
  

   shells 
  have 
  the 
  hinge 
  of 
  Chione 
  and 
  Venus, 
  a 
  strong 
  radial 
  sculpture 
  

   which 
  is 
  seldom 
  found 
  in 
  Tapes, 
  and 
  crenulated 
  valve-margins, 
  

   I 
  regard 
  them 
  as 
  very 
  closely 
  allied 
  to 
  the 
  two 
  former 
  groups, 
  and 
  

   very 
  distinct 
  from 
  the 
  last. 
  

  

  Protothaca 
  only 
  differs 
  from 
  Venus 
  in 
  having 
  a 
  strong 
  radial 
  

   sculpture 
  and 
  in 
  the 
  absence 
  of 
  rugosities 
  on 
  the 
  posterior 
  teeth, 
  but 
  

   the 
  latter 
  character 
  is 
  not 
  of 
  generic 
  importance, 
  for 
  such 
  rugosities 
  

   are 
  present 
  in 
  several 
  .species 
  of 
  Chione. 
  Again, 
  while 
  the 
  typical 
  

   section 
  of 
  Chione 
  has 
  strong 
  radial 
  structure, 
  other 
  sections 
  have 
  only 
  

   concentric 
  ribs 
  or 
  riblets. 
  If 
  all 
  are 
  regarded 
  as 
  included 
  in 
  the 
  

  

  