﻿100 
  PROCEEDINGS 
  OF 
  THE 
  61 
  ALACOLOGICAL 
  SOCIETY. 
  

  

  The 
  radula 
  closely 
  resembles 
  that 
  of 
  such 
  species 
  of 
  Thais 
  proper 
  

   as 
  are 
  uot 
  famished 
  with 
  denticles, 
  but 
  have 
  three 
  bare 
  cusps. 
  

  

  CoNcnoLEPAs, 
  Lamarck. 
  

  

  Tlie 
  radula 
  of 
  tlie 
  single 
  species 
  {penivianus, 
  Lam.) 
  is 
  of 
  the 
  

   normal 
  Thais 
  type; 
  central 
  cusp 
  long 
  and 
  ruthor 
  narrow; 
  side 
  cusps 
  

   largo, 
  almost 
  as 
  long 
  as 
  the 
  central, 
  with 
  a 
  strong, 
  rather 
  blunt 
  

   denticle 
  low 
  down 
  on 
  the 
  inside; 
  outside, 
  4-5 
  rather 
  small 
  denticles, 
  

   two 
  of 
  which 
  climb 
  ; 
  knob 
  strong 
  but 
  prominent 
  ; 
  base 
  simple, 
  

   straight. 
  

  

  The 
  radula 
  is 
  very 
  long 
  ; 
  I 
  have 
  counted 
  260 
  + 
  nascent 
  rows. 
  

  

  PiNAXiA, 
  A. 
  Adams. 
  

   The 
  radula 
  of 
  the 
  single 
  species 
  {coronata, 
  A. 
  Ad.) 
  is 
  of 
  the 
  

   normal 
  Thais 
  type; 
  cusps 
  short 
  aTid 
  thick; 
  side 
  cusps 
  strongly 
  

   singly 
  denticled 
  inside 
  ; 
  at 
  least 
  three 
  denticles 
  outside, 
  one 
  of 
  them 
  

   climbing 
  ; 
  knob 
  very 
  prominent 
  ; 
  base 
  simple, 
  slightly 
  curved 
  

   inward. 
  (Fig. 
  27.) 
  

  

  Agnewia, 
  Tenison- 
  Woods. 
  

   Tlie 
  radula 
  of 
  the 
  single 
  species, 
  tritoniformis, 
  Blainv., 
  is 
  essentially 
  

   Thaidan 
  ; 
  central 
  cusp 
  long, 
  broad 
  and 
  rather 
  thick 
  ; 
  side 
  cusps 
  about 
  

   lialf 
  the 
  length, 
  broad, 
  with 
  a 
  strong, 
  rather 
  blunt 
  denticle 
  about 
  

   half-way 
  up 
  on 
  the 
  inside; 
  outside, 
  3-4 
  well-marked 
  denticles; 
  

   knob 
  prominent; 
  base 
  slightly 
  arched. 
  (Fig. 
  26.) 
  

  

  DjiuPA, 
  Bolten. 
  

  

  Conchologically, 
  the 
  precise 
  limits 
  of 
  this 
  genus 
  are 
  somewhat 
  

   ill-defined, 
  as 
  between 
  Thais 
  on 
  the 
  one 
  side 
  and 
  Morula 
  on 
  the 
  

   other. 
  The 
  radula 
  enables 
  us 
  to 
  separate 
  off 
  with 
  confidence, 
  under 
  

   Drupa, 
  a 
  certain 
  number 
  of 
  species 
  as 
  closely 
  allied 
  to 
  Thais, 
  and 
  as 
  

   definitely 
  distinct 
  from 
  Morula. 
  

  

  The 
  rhachidian 
  cusps 
  are, 
  as 
  a 
  rule, 
  long, 
  but 
  not 
  very 
  thick 
  or 
  

   prominent, 
  as 
  they 
  often 
  are 
  in 
  Thais; 
  the 
  side 
  cusps 
  are 
  not, 
  as 
  

   a 
  rule, 
  greatly 
  shorter 
  than 
  the 
  central; 
  the 
  denticle 
  on 
  the 
  side 
  

   cusps 
  is 
  deeply 
  cut, 
  and 
  its 
  point 
  often 
  curves 
  towards 
  the 
  cusp 
  ; 
  the 
  

   small 
  outside 
  denticles 
  are 
  well 
  marked, 
  sometimes 
  climbing, 
  some- 
  

   times 
  not; 
  the 
  base, 
  though 
  as 
  a 
  rule 
  slightly 
  waved 
  in 
  the 
  centre, 
  

   is 
  that 
  of 
  Thais, 
  and 
  not 
  that 
  of 
  Morula, 
  and 
  is 
  not 
  indented 
  by 
  the 
  

   prolongation 
  of 
  the 
  root 
  of 
  tlie 
  central 
  cusp. 
  The 
  blade 
  of 
  the 
  

   laterals 
  is 
  long 
  and 
  thin. 
  

  

  affinis, 
  Pease 
  (so 
  I 
  regard 
  the 
  species 
  labelled 
  rugosa, 
  Quoy, 
  the 
  

   original 
  shells 
  being 
  in 
  ray 
  possession): 
  Funafuti. 
  llhachidian 
  

   somewhat 
  transparent, 
  all 
  tlie 
  cusps 
  narrow 
  and 
  sharp, 
  central 
  

   scarcely 
  longer 
  than 
  the 
  side 
  cusps, 
  which 
  are 
  strongly 
  sharply 
  

   denticled 
  low 
  down 
  on 
  the 
  inside; 
  outside, 
  4-5 
  prominent 
  small 
  

   denticles, 
  rather 
  deeply 
  cut, 
  the 
  innermost 
  climbing; 
  knob 
  blunt, 
  

   rather 
  elevated. 
  

  

  clathrata, 
  Lam. 
  : 
  S. 
  Pacific. 
  Median 
  cusp 
  rather 
  short, 
  very 
  

   broadly 
  triangular, 
  not 
  very 
  much 
  longer 
  than 
  the 
  side 
  cusps, 
  which 
  

   are 
  narrower 
  and 
  sharply 
  pointed; 
  a 
  prominent 
  but 
  rather 
  blunt 
  

  

  