﻿COOKE 
  : 
  ON 
  EADULA 
  OF 
  EUTHRIA. 
  233 
  

  

  7 
  species 
  from 
  New 
  Zealand 
  and 
  the 
  outlying 
  islands, 
  and 
  there 
  is 
  at 
  

   least 
  1 
  Tasmanian 
  species 
  ; 
  Bartsch 
  enumerates 
  ^ 
  9 
  more 
  from 
  the 
  

   Cape 
  ; 
  4 
  species, 
  perhaps 
  not 
  all 
  of 
  them 
  Euthria, 
  have 
  been 
  

   described 
  ■ 
  from 
  Japan, 
  there 
  is 
  1 
  from 
  Iverguelin 
  Island 
  {chlorotica, 
  

   Marts.), 
  and 
  an 
  outlying 
  species, 
  not 
  always 
  regarded 
  as 
  Euthria 
  

   {(lira, 
  Reeve), 
  ranges 
  from 
  Puget 
  Sound 
  to 
  the 
  Californian 
  islands. 
  

   The 
  Magellanic 
  region, 
  including 
  tlie 
  Ealklands, 
  ap])ears 
  to 
  be 
  

   the 
  nucleus 
  of 
  a 
  ricli 
  development 
  of 
  Euthria. 
  Strebel, 
  under 
  the 
  _ 
  

   groups 
  Fareuthria, 
  Ghjpteuthria, 
  and 
  Anomacme, 
  has 
  enumerated' 
  

   17 
  species 
  from 
  this 
  region, 
  and 
  Thiele^ 
  and 
  E. 
  A. 
  Smitli 
  * 
  have 
  

   added 
  1 
  and 
  2 
  respectively. 
  Even 
  so, 
  the 
  list 
  of 
  species 
  described 
  is 
  

   probably 
  not 
  exhausted. 
  

  

  Of 
  the 
  forty-three 
  species 
  mentioned 
  above, 
  the 
  radula 
  of 
  cornea 
  

   was 
  figured 
  hj 
  Troscliel^ 
  {Gebiss 
  der 
  Schnecken, 
  ii, 
  pi. 
  vii, 
  f. 
  11). 
  

   Hutton 
  has 
  figured 
  the 
  radula 
  oi 
  flarescens, 
  litiea, 
  striata, 
  and 
  titlata, 
  

   and, 
  doubtfully, 
  of 
  litlorinoides? 
  Troschel 
  figures 
  (pi. 
  vii, 
  f. 
  12) 
  as 
  

   of 
  lineata, 
  Chem. 
  (^linea, 
  Mart.), 
  a 
  radula 
  which 
  is 
  certainly 
  that 
  of 
  

   littorinoides. 
  Thiele 
  has 
  figured 
  ^ 
  the 
  radula 
  of 
  Fareuthria 
  innocens, 
  

   Smith. 
  

  

  In 
  illustration 
  of 
  the 
  present 
  paper 
  the 
  radulce 
  of 
  ten 
  species 
  

   are 
  figured, 
  seven 
  of 
  them 
  for 
  the 
  first 
  time. 
  All 
  are 
  from 
  the 
  

   collection 
  of 
  the 
  late 
  Professor 
  H. 
  M. 
  Gwatkin. 
  The 
  results 
  suggest 
  

   that 
  the 
  forms 
  hitlierto 
  grouped 
  under 
  Euthria 
  are 
  susceptible 
  of 
  

   considerable 
  subdivision, 
  and 
  tliat 
  some 
  must 
  probably 
  be 
  removed 
  

   from 
  that 
  genus 
  altogether. 
  

  

  The 
  specimens 
  examined 
  fall 
  into 
  four 
  distinct 
  groups. 
  

  

  Group 
  1. 
  — 
  llhachidian 
  tooth 
  tricuspid, 
  cusps 
  somewhat 
  blunt, 
  

   elevated, 
  base 
  sloping 
  away 
  rapidly, 
  slope 
  interrupted 
  on 
  each 
  side 
  

   by 
  a 
  blunt 
  knob 
  or 
  tooth, 
  base 
  deeply 
  arched 
  below 
  ; 
  laterals 
  

   tricuspid, 
  simple, 
  not 
  much 
  curved. 
  To 
  this 
  type 
  belong 
  cornea, 
  L., 
  

   and 
  linea, 
  Mart. 
  

  

  1 
  Bull. 
  U.S. 
  Nat. 
  Mus., 
  91, 
  1915. 
  

  

  '^ 
  E. 
  badia, 
  A. 
  Ad., 
  lirata, 
  A. 
  Ad., 
  Journ. 
  Linn. 
  Soc. 
  Lend., 
  vii, 
  1863, 
  

   p. 
  108 
  ; 
  Bucclnum 
  ferreum, 
  Reeve, 
  Concli. 
  Icon., 
  iii, 
  1847, 
  Bucc. 
  f. 
  102 
  ; 
  

   Euthria 
  fuscolabiata, 
  Smith, 
  Ann. 
  Mag. 
  Nat. 
  Hist., 
  ser. 
  iv, 
  vol. 
  xv, 
  1875, 
  

   p. 
  421. 
  

  

  = 
  Zool. 
  Jabrb., 
  Syst. 
  xxii, 
  1905, 
  p. 
  599 
  f. 
  ; 
  Wissensch. 
  Ergebn. 
  Schwed. 
  

   Siidpol. 
  Exped., 
  vol. 
  vi, 
  pt. 
  i, 
  1908, 
  p. 
  28. 
  Strebel's 
  groups 
  are 
  founded 
  

   solely 
  on 
  supposed 
  conchological 
  differences, 
  mainly 
  of 
  structure. 
  "The 
  

   genus," 
  he 
  remarks, 
  "includes 
  species 
  of 
  such 
  different 
  forms 
  that 
  

   a 
  revision 
  and 
  fresh 
  grouping 
  appears 
  necessary." 
  He 
  admits 
  that 
  the 
  

   systematic 
  value 
  of 
  the 
  groups 
  he 
  names, 
  Fareuthria, 
  Glyptcuthria, 
  etc., 
  

   is 
  questionable, 
  without 
  any 
  simultaneous 
  knowledge 
  of 
  their 
  anatomical 
  

   relations. 
  

  

  * 
  Fareuthria 
  plicatula, 
  Thiele, 
  Deutsch. 
  Siidpol. 
  Exped., 
  vol. 
  xiii, 
  1912, 
  p. 
  212. 
  

  

  * 
  Thesbiai'!) 
  innocens, 
  Smith, 
  Nat. 
  Antarct. 
  Exped. 
  1901-4, 
  vol. 
  ii, 
  1907, 
  

  

  Moll. 
  Gastrop., 
  p. 
  4, 
  pi. 
  i, 
  f. 
  1 
  ; 
  Euthria 
  atrata, 
  Smith, 
  Proc. 
  Zool. 
  Soc. 
  

  

  Lond., 
  1881, 
  p. 
  29, 
  pi. 
  iv, 
  fig. 
  5. 
  

   ^ 
  Troschel's 
  figure 
  of 
  Euthria 
  lineata, 
  Chem. 
  (Gebiss, 
  vol. 
  ii, 
  pi. 
  vii, 
  f. 
  12), 
  

  

  represents 
  by 
  mistake 
  some 
  other 
  radula. 
  

   ^ 
  Trans. 
  New 
  Zealand 
  Inst., 
  vols, 
  xiv, 
  xv, 
  xvi. 
  

   « 
  Deutsch. 
  Siidpol. 
  Exped., 
  vol. 
  xiii, 
  1912, 
  p. 
  212, 
  pi. 
  xvi, 
  f. 
  22. 
  

  

  