﻿462 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  103 
  

  

  in 
  the 
  number 
  of 
  whorls 
  in 
  the 
  operculum 
  to 
  a 
  degree 
  where 
  it 
  has 
  

   become 
  multispiral. 
  

  

  It 
  should 
  be 
  pointed 
  out 
  that 
  Kesteven 
  included 
  the 
  genus 
  Peasiella 
  

   Neville 
  in 
  the 
  famUy 
  Modulidae. 
  Although 
  further 
  anatomical 
  study- 
  

   is 
  needed 
  on 
  this 
  genus, 
  I 
  would 
  be 
  inclined 
  (with 
  the 
  radular 
  and 
  

   opercular 
  characters 
  presented 
  by 
  Kesteven, 
  1903, 
  p. 
  633) 
  to 
  include 
  

   Peasiella 
  in 
  the 
  family 
  Littorinidae 
  and 
  in 
  a 
  higher 
  phylogenetic 
  

   position 
  than 
  the 
  genus 
  Echininus. 
  Kesteven 
  also 
  erected 
  a 
  new 
  

   family, 
  the 
  Risellidae, 
  for 
  the 
  inclusion 
  of 
  Risella 
  Gray 
  (now 
  Bembicium 
  

   Philippi) 
  and 
  Risellopsis 
  Kesteven, 
  1902 
  (not 
  Cossmann, 
  1908, 
  which 
  

   was 
  renamed 
  Riselloidea 
  Cossmann, 
  1909). 
  The 
  new 
  famUy 
  name, 
  

   Bembiciidae, 
  was 
  introduced 
  by 
  A. 
  W. 
  B. 
  Powell 
  (1937, 
  p. 
  67). 
  

   Before 
  accepting 
  this 
  family, 
  it 
  would 
  be 
  best 
  to 
  have 
  an 
  anatomical 
  

   study 
  made, 
  and, 
  in 
  the 
  meanwhile, 
  allow 
  it 
  to 
  remain 
  in 
  the 
  family 
  

   Littormidae 
  as 
  do 
  J. 
  Thiele 
  and 
  W. 
  Wenz. 
  

  

  Genus 
  Tectarius 
  Valenciennes, 
  1833 
  

  

  Subgenus 
  Cenchrites 
  von 
  Martens, 
  1900 
  

   Tectarius 
  muricatus 
  Linne 
  

  

  Tectarius 
  muricatus 
  Linn6, 
  Systema 
  naturae, 
  ed. 
  10, 
  vol. 
  1, 
  1758. 
  

  

  Observations 
  on 
  living 
  specimens 
  from 
  Vedado, 
  Habana, 
  Cuba, 
  

   show 
  that 
  the 
  animal 
  is 
  typically 
  littorinid. 
  The 
  tentacles 
  are 
  one- 
  

   third 
  longer 
  than 
  the 
  extended 
  proboscis, 
  are 
  cylindrical 
  and 
  tapering, 
  

   translucent 
  gray 
  in 
  color 
  with 
  faint 
  circular 
  bars 
  of 
  brown. 
  The 
  

   proboscis 
  is 
  dark 
  brown. 
  The 
  mantle 
  edge 
  is 
  thickened, 
  cream 
  yellow 
  

   in 
  color, 
  and 
  slightly 
  undulatory. 
  The 
  sides 
  of 
  the 
  foot 
  are 
  light 
  

   slate-gray 
  with 
  numerous, 
  fine, 
  clusters 
  of 
  chalk-white, 
  embedded 
  

   granules. 
  Underside 
  of 
  foot 
  is 
  slate 
  gray. 
  

  

  The 
  mode 
  of 
  foot 
  progression 
  is 
  ditaxic 
  with 
  a 
  few 
  simultaneous 
  

   retrograde 
  waves; 
  that 
  is, 
  the 
  sole 
  of 
  the 
  foot 
  is 
  divided 
  down 
  its 
  

   length 
  from 
  anterior 
  to 
  posterior 
  by 
  a 
  faint 
  fissure, 
  and 
  each 
  side 
  

   half 
  acts 
  independently 
  of 
  the 
  other 
  much 
  in 
  the 
  manner 
  of 
  a 
  person 
  

   shuffling 
  forward 
  with 
  his 
  feet 
  in 
  a 
  potato 
  sack. 
  On 
  each 
  half, 
  a 
  

   dark 
  wave 
  appears 
  at 
  the 
  anterior 
  end 
  at 
  the 
  same 
  time 
  and 
  moves 
  

   towards 
  the 
  posterior 
  end 
  (retrograde 
  wave). 
  A 
  bibliography 
  con- 
  

   cerning 
  this 
  subject 
  is 
  given 
  by 
  H. 
  W. 
  Lissmann 
  (1945). 
  This 
  same 
  

   type 
  of 
  progression 
  was 
  reported 
  for 
  Littorina 
  littorea 
  Linne 
  (Vies, 
  

   1907; 
  Parker, 
  1911), 
  Littorina 
  saxatilis 
  Olivi 
  (as 
  L. 
  rudis 
  Maton), 
  and 
  

   Nodilittorina 
  tuberculata 
  Menke 
  (as 
  Tectarius 
  nodulosus 
  from 
  Bermuda) 
  

   (Parker, 
  1911). 
  

  

  The 
  penis 
  of 
  Tectarius 
  muricatus 
  is 
  the 
  simplest 
  of 
  the 
  littorinids 
  I 
  

   have 
  examined 
  from 
  the 
  Western 
  Atlantic, 
  and, 
  except 
  for 
  the 
  absence 
  

   of 
  sawlike 
  frills 
  on 
  one 
  edge, 
  it 
  is 
  not 
  unlike 
  that 
  of 
  Littorina 
  littorea 
  

  

  