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  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  loa 
  

  

  of 
  the 
  penis. 
  On 
  both 
  sides 
  of 
  the 
  penis, 
  in 
  the 
  region 
  near 
  the 
  acces- 
  

   sory 
  flagellum, 
  the 
  surface 
  bears 
  numerous, 
  small, 
  fleshy, 
  opaque-white 
  

   papillae. 
  These 
  are 
  absent 
  in 
  Nodilittorina 
  and 
  Tectarius 
  muricatus. 
  

   The 
  posterior 
  edge 
  of 
  the 
  penis 
  bears 
  a 
  narrow, 
  nearly 
  sealed 
  

   seminal 
  groove 
  which 
  ends 
  near 
  the 
  distal 
  end 
  of 
  the 
  penis, 
  and 
  which 
  

   has 
  its 
  origin 
  on 
  the 
  side 
  of 
  the 
  body 
  some 
  2 
  mm. 
  from 
  the 
  base 
  of 
  the 
  

   penis. 
  The 
  region 
  of 
  the 
  prostate 
  gland 
  on 
  the 
  right 
  border 
  oi 
  the 
  

   mantle 
  is 
  cobalt 
  blue 
  in 
  color. 
  In 
  mature 
  females, 
  this 
  region 
  bears 
  

   the 
  swollen, 
  elongate, 
  opaque-white 
  accessory 
  gland. 
  

  

  Radula. 
  — 
  The 
  radula 
  of 
  Echininus 
  nodulosus 
  Pfeiffer 
  (fig. 
  57, 
  a) 
  is 
  

   very 
  distinctive, 
  although 
  it 
  conforms 
  in 
  general 
  pattern 
  to 
  those 
  

   found 
  in 
  the 
  family 
  Littormidae, 
  The 
  reduction 
  of 
  the 
  central 
  tooth 
  

   is 
  most 
  remarkable 
  in 
  that 
  it 
  has 
  become 
  a 
  short, 
  thin, 
  sliverlike 
  

   tooth. 
  The 
  main 
  function 
  of 
  rasping 
  has 
  been 
  taken 
  over 
  by 
  the 
  

   greatly 
  enlarged, 
  coarse 
  lateral 
  teeth. 
  The 
  inner 
  and 
  especially 
  the 
  

   outer 
  marginal 
  teeth 
  are 
  somewhat 
  reduced. 
  The 
  tendency 
  to 
  reduce 
  

   the 
  central 
  tooth 
  appears 
  to 
  be 
  a 
  development 
  arising 
  perhaps 
  through 
  

   the 
  Nodilittorina 
  stock. 
  The 
  radula 
  of 
  Echininus 
  cumingi 
  from 
  the 
  

   Indo-Pacific 
  has 
  a 
  reduced 
  central 
  tooth 
  (fide 
  Troschel, 
  1858, 
  pi. 
  11, 
  

   fig. 
  7) 
  and 
  enlarged 
  lateral 
  teeth. 
  Among 
  the 
  Nodilittorina, 
  our 
  

   Atlantic 
  A^. 
  tuberculata 
  Menke 
  has 
  a 
  strongly 
  compressed, 
  elongate 
  

   central 
  tooth 
  (fig. 
  57, 
  b). 
  The 
  Indo-Pacific 
  A^. 
  pyramidalis 
  has 
  a 
  

   much 
  less 
  reduced 
  central 
  tooth 
  which 
  closely 
  resembles 
  that 
  in 
  the 
  

   members 
  of 
  the 
  subgenus 
  Melarhaphe. 
  It 
  may 
  be 
  noted 
  that 
  mem- 
  

   bers 
  of 
  such 
  species 
  as 
  Littorina 
  (Littorina) 
  littorea 
  Linne 
  and 
  irrorata 
  

   Say 
  have 
  a 
  well-developed, 
  almost 
  square 
  central 
  tooth. 
  

  

  The 
  radula 
  ribbon 
  of 
  Echininus 
  nodulosus 
  measured 
  115 
  mm. 
  in 
  

   length 
  in 
  one 
  specimen, 
  110 
  mm. 
  in 
  another. 
  This 
  is 
  7 
  to 
  8 
  times 
  the 
  

   length 
  of 
  the 
  shell. 
  The 
  ribbon 
  is 
  twice 
  the 
  width 
  of 
  that 
  found 
  in 
  a 
  

   Nodilittorina 
  tuberculata 
  Menke 
  of 
  the 
  same 
  shell 
  size. 
  The 
  number 
  

   of 
  transverse 
  rows 
  is 
  about 
  1,250. 
  In 
  A^. 
  tuberculata 
  there 
  were 
  about 
  

   1,225 
  rows, 
  in 
  Tectarius 
  muricatus 
  1,500 
  rows 
  in 
  a 
  ribbon 
  67 
  mm. 
  in 
  

   length. 
  Pelseneer 
  (Mollusca, 
  Treatise 
  in 
  Zoology, 
  1906) 
  reports 
  

   3,600 
  rows 
  m 
  Littorina 
  littorea. 
  I 
  do 
  not 
  know 
  if 
  there 
  is 
  any 
  phylo- 
  

   genetic 
  or 
  ecological 
  significance 
  to 
  these 
  various 
  number 
  of 
  rows. 
  

  

  Geographical 
  Distribution. 
  — 
  The 
  range 
  of 
  this 
  species 
  is 
  presented 
  in 
  

   figm'e 
  56, 
  6, 
  and 
  its 
  restricted 
  distribution 
  is 
  discussed 
  in 
  the 
  remarks 
  

   under 
  Nodilittorina 
  tuberculata. 
  The 
  species 
  is 
  usually 
  abundant 
  

   where 
  it 
  occurs. 
  

  

  New 
  records. 
  — 
  Florida: 
  Stock 
  Island, 
  Key 
  West 
  (C. 
  I. 
  Aslakson); 
  

   Indian 
  Key; 
  Fortune 
  Island 
  (P. 
  Bartsch). 
  Bahamas: 
  Nassau, 
  New 
  

   Providence 
  Island 
  (H. 
  Dodge); 
  South 
  Bight, 
  Andros 
  Island 
  (P. 
  

   Bartsch); 
  Pimlico 
  Island, 
  Racoon 
  Cay, 
  Ragged 
  Islands 
  (P. 
  Bartsch). 
  

   Cuba: 
  Cape 
  Cajon; 
  Santa 
  Cruz; 
  Cienfuegos 
  Harbor; 
  Santiago 
  de 
  

  

  