﻿REVIEW 
  OF 
  THE 
  ATLANTIC 
  PERIWINKLES 
  — 
  ABBOTT 
  461 
  

  

  Cuba. 
  Jamaica: 
  Robins 
  Bay, 
  St. 
  Marys; 
  Montego 
  Bay, 
  St. 
  James; 
  

   Port 
  Henderson; 
  Annotta 
  Bay 
  (all 
  C. 
  R. 
  Orcutt). 
  Hispaniola: 
  

   Morne 
  Rouge, 
  southwestern 
  Haiti; 
  Beata 
  Island 
  (A. 
  Wetmore). 
  

   Puerto 
  Rico: 
  Rincon 
  Lighthouse, 
  Mona 
  Passage 
  (G. 
  L. 
  Warmke 
  

   and 
  N. 
  T. 
  Mattox). 
  Virgin 
  Islands: 
  St. 
  Croix 
  (H. 
  F. 
  Dunn). 
  

   Caribbean 
  Islands: 
  Navassa 
  Island. 
  (All 
  records 
  USNM.) 
  

  

  Phylogenetic 
  position 
  of 
  Echininus. 
  — 
  From 
  the 
  anatomical 
  evidence 
  

   presented 
  here, 
  it 
  appears 
  that 
  there 
  is 
  little 
  doubt 
  that 
  Echininus 
  has 
  

   many 
  characters 
  that 
  are 
  typically 
  littorinid. 
  This 
  is 
  especially 
  true 
  

   in 
  the 
  case 
  of 
  the 
  long 
  radula 
  ribbon, 
  the 
  form 
  of 
  the 
  teeth, 
  the 
  pres- 
  

   ence 
  of 
  an 
  open 
  seminal 
  groove 
  (instead 
  of 
  a 
  closed, 
  internal 
  seminal 
  

   canal) 
  on 
  the 
  penis, 
  and 
  the 
  simple 
  tentacles 
  with 
  the 
  eye 
  set 
  near 
  

   the 
  base. 
  We 
  reject 
  Kesteven's 
  (1903) 
  placement 
  of 
  this 
  genus 
  in 
  

   the 
  family 
  Modulidae. 
  He 
  did 
  so 
  on 
  two 
  characters 
  — 
  the 
  tooth 
  on 
  

   the 
  base 
  of 
  the 
  columella, 
  and 
  the 
  multispiral 
  operculum. 
  However, 
  

   Kesteven 
  was 
  in 
  error 
  in 
  stating 
  that 
  members 
  of 
  the 
  genus 
  Echininus 
  

   (Echinella, 
  as 
  he 
  called 
  it) 
  have 
  a 
  small 
  tooth 
  at 
  the 
  base 
  of 
  the 
  col- 
  

   umella. 
  It 
  is 
  only 
  in 
  the 
  Tectarius, 
  sensu 
  stricto, 
  group 
  (with 
  

   paucispiral 
  opercula) 
  such 
  as 
  T. 
  coronarius 
  Lamarck, 
  that 
  we 
  find 
  a 
  

   basal 
  tooth. 
  This 
  leaves 
  only 
  the 
  multispu-al 
  operculum 
  as 
  a 
  character 
  

   in 
  common 
  with 
  Modulus, 
  and 
  although 
  this 
  character 
  may 
  be 
  of 
  

   convenient 
  generic 
  value 
  in 
  some 
  cases, 
  it 
  certainly 
  is 
  not 
  always 
  

   a 
  family 
  character. 
  

  

  I 
  believe 
  that 
  the 
  following 
  characters 
  found 
  in 
  Modulus, 
  and 
  

   absent 
  in 
  Echininus, 
  exclude 
  the 
  latter 
  from 
  the 
  family 
  Modulidae: 
  

   Eyes 
  located 
  half 
  way 
  up 
  the 
  length 
  of 
  the 
  tentacles, 
  small 
  digitations 
  

   along 
  the 
  border 
  of 
  the 
  mantle 
  edge 
  (Abbott, 
  1944, 
  pi. 
  1) 
  ; 
  female 
  with 
  

   an 
  "ovipositor" 
  organ 
  on 
  the 
  right 
  side 
  of 
  the 
  body; 
  radula 
  relatively 
  

   short 
  (100 
  to 
  150 
  transverse 
  rows) 
  with 
  a 
  thin, 
  oval, 
  7-den 
  tided 
  

   central 
  tooth; 
  a 
  lateral 
  and 
  two 
  marginal 
  teeth 
  which 
  are 
  denticulated 
  

   (the 
  entire 
  radula 
  closely 
  resembles 
  that 
  m 
  the 
  Rissoacea). 
  Al- 
  

   though 
  not 
  necessarily 
  of 
  phylogenetic 
  importance, 
  it 
  may 
  be 
  pointed 
  

   out 
  that 
  the 
  feces 
  of 
  many, 
  if 
  not 
  aU, 
  Littorinidae 
  are 
  relatively 
  short 
  

   (2 
  or 
  3 
  times 
  as 
  long 
  as 
  wide) 
  and 
  are 
  lined 
  up 
  in 
  the 
  rectum, 
  one 
  

   directly 
  behind 
  the 
  other, 
  while 
  in 
  Modulus 
  modulus 
  Linn6 
  the 
  feces 
  

   are 
  quite 
  long 
  (5 
  or 
  6 
  times 
  as 
  long 
  as 
  wide) 
  and 
  are 
  closely 
  packed 
  

   side 
  by 
  side 
  at 
  an 
  oblique 
  angle 
  in 
  the 
  rectum, 
  as 
  in 
  the 
  Thiaridae. 
  

  

  In 
  summary 
  of 
  the 
  position 
  of 
  Echininus, 
  I 
  am 
  inclined 
  to 
  consider 
  

   it 
  a 
  specialization 
  of 
  the 
  ancestral 
  stock 
  of 
  the 
  Melarhaphe 
  group 
  in 
  

   the 
  family 
  Littorinidae 
  which 
  has 
  shown 
  a 
  tendency 
  towards 
  the 
  

   abortion 
  of 
  the 
  central 
  tooth 
  in 
  the 
  radula, 
  an 
  enlargement 
  and 
  closer 
  

   juxtaposition 
  of 
  the 
  marginals, 
  the 
  reduction 
  of 
  the 
  ditaxic 
  fissure 
  in 
  

   the 
  foot, 
  a 
  reduction 
  in 
  the 
  size 
  of 
  the 
  osphradium, 
  and 
  the 
  increase 
  

  

  