﻿52 
  W. 
  E. 
  KANDLE.S. 
  

  

  are 
  spread 
  out 
  iu 
  a 
  fan-like 
  manner^ 
  and 
  constitute 
  the 
  

   flabelliform 
  teeth 
  (fig. 
  27). 
  

  

  It 
  will 
  be 
  seen 
  on 
  examination 
  of 
  figs. 
  28 
  and 
  29 
  that 
  the 
  

   radula? 
  of 
  T. 
  striatus 
  and 
  T. 
  exasperatus 
  approximate 
  

   more 
  nearly 
  to 
  the 
  Gibbula 
  than 
  to 
  the 
  Calliostoma 
  tjpe, 
  

   in 
  that 
  the 
  cusps 
  of 
  the 
  central 
  and 
  lateral 
  teeth 
  are 
  unscrratedj 
  

   but 
  bear 
  on 
  their 
  distal 
  margins 
  very 
  distinct 
  notches, 
  such 
  as 
  

   are 
  present 
  in 
  T. 
  magus. 
  

  

  It 
  is 
  almost 
  impossible 
  to 
  compare 
  the 
  radula 
  of 
  Trochus 
  

   with 
  that 
  of 
  Pleurotomaria, 
  as 
  in 
  the 
  latter 
  we 
  find 
  no 
  

   trace 
  of 
  the 
  clearly 
  marked 
  regions 
  which 
  the 
  radula 
  of 
  

   Trochus 
  presents. 
  The 
  radula 
  of 
  Pleurotomaria 
  is 
  also 
  

   obviously 
  specialised 
  in 
  the 
  possession 
  of 
  such 
  extremely 
  

   modified 
  structures 
  as 
  the 
  brush 
  and 
  lamellate 
  teeth. 
  A 
  

   peculiar 
  feature 
  of 
  the 
  Pleurotomariau 
  radula 
  is 
  the 
  presence 
  

   of 
  a 
  series 
  of 
  accessory 
  basal 
  plates, 
  situated 
  underneath, 
  and 
  

   alternating 
  with 
  the 
  bases 
  of 
  the 
  uncinate 
  teeth 
  (Woodward, 
  

   45, 
  p. 
  2-52, 
  fig. 
  32). 
  A 
  similar 
  series 
  of 
  basal 
  plates 
  is 
  present 
  

   in 
  the 
  radula 
  of 
  Trochus, 
  occupying 
  a 
  corresponding 
  

   position, 
  viz. 
  at 
  the 
  base 
  of 
  the 
  uncinate 
  or 
  marginal 
  teeth. 
  

  

  The 
  salivary 
  glands 
  are 
  slightly 
  different 
  in 
  the 
  two 
  

   sub-genera 
  Gibbula 
  and 
  Calliostoma. 
  In 
  the 
  former 
  they 
  

   are 
  small 
  rod-like 
  bodies 
  (figs. 
  39, 
  40, 
  si. 
  g.) 
  lying 
  on 
  the 
  

   dorso-lateral 
  surfaces 
  of 
  tlie 
  an(;erior 
  portion 
  of 
  the 
  crop, 
  and 
  

   opening 
  into 
  the 
  buccal 
  mass 
  slightly 
  in 
  front 
  of 
  the 
  cerebi-al 
  

   conimissnre. 
  In 
  T. 
  zi/yphinus 
  (fig. 
  44, 
  sJ. 
  g.) 
  and 
  other 
  

   species 
  of 
  Calliostoma 
  the 
  salivary 
  glands 
  are 
  larger 
  and 
  

   racemose. 
  The 
  duct 
  opens 
  into 
  the 
  buccal 
  cavity 
  immediately 
  

   over 
  the 
  anterior 
  end 
  of 
  the 
  odontophore. 
  

  

  The 
  Crop. 
  — 
  The 
  anterior 
  portion 
  of 
  the 
  alimentary 
  caualis 
  

   enlarged 
  to 
  form 
  the 
  crop 
  (fig. 
  39, 
  cr.) 
  ; 
  upon 
  the 
  dorsal 
  

   surface 
  a 
  rod-like 
  area 
  can 
  be 
  distinguished, 
  which 
  curves 
  

   over 
  from 
  the 
  mid-line 
  towards 
  the 
  left 
  side, 
  eventually 
  

   becoming 
  ventral 
  in 
  position. 
  

  

  Communicating 
  with 
  the 
  crop 
  are 
  two 
  lateral 
  diverticula, 
  

   viz. 
  the 
  right 
  and 
  left 
  oesophageal 
  pouches, 
  the 
  former 
  being 
  

   the 
  larpfer. 
  

  

  