﻿366 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  loa 
  

  

  the 
  great 
  similarity 
  of 
  shells, 
  Guhaedomus 
  does 
  not 
  belong 
  here. 
  Ani- 
  

   mal 
  characters 
  prove 
  it 
  to 
  belong 
  in 
  the 
  family 
  Thiaridae, 
  as 
  recorded 
  

   below. 
  Oxymelania 
  is 
  known 
  to 
  range 
  geographically 
  from 
  the 
  Panuco 
  

   River 
  system 
  of 
  Mexico 
  to 
  the 
  headwaters 
  of 
  the 
  Usumasinta 
  River 
  

   in 
  Guatemala. 
  

  

  Subgenus 
  Pachychilus 
  Lea, 
  sensu 
  stricto, 
  1851 
  

  

  Pachychilus 
  Lea 
  (Lea 
  and 
  Lea, 
  1851, 
  p. 
  179) 
  originally 
  included 
  

   only 
  two 
  specific 
  names, 
  cumingii 
  Lea 
  and 
  laevissima 
  Sowerby. 
  In 
  

   January 
  1860, 
  Reeve 
  (1859-1861, 
  pi. 
  18, 
  fig. 
  126) 
  designated 
  laevissima 
  

   as 
  the 
  genotype. 
  On 
  the 
  other 
  hand, 
  Reeve's 
  "laevissima" 
  was 
  a 
  

   mixture 
  of 
  the 
  species 
  from 
  Chiapas, 
  Mexico, 
  which 
  has 
  since 
  been 
  

   mistakenly 
  called 
  "laevissima" 
  by 
  many 
  authors, 
  and 
  the 
  true 
  laevis- 
  

   sima 
  of 
  Sowerby 
  and 
  Lea 
  from 
  La 
  Guayra, 
  Venezuela. 
  Since 
  the 
  

   mixture 
  of 
  Reeve 
  contained 
  in 
  synonymy 
  the 
  originally 
  included 
  

   laevissima 
  of 
  Sowerby, 
  this 
  designation 
  was 
  valid. 
  Thus 
  the 
  genotype, 
  

   correctly 
  figured 
  on 
  plate 
  19, 
  figure 
  133c, 
  of 
  Reeve 
  (1859-1861) 
  is 
  

   the 
  only 
  known 
  South 
  American 
  species 
  of 
  the 
  genus. 
  The 
  typical 
  

   group 
  in 
  Central 
  America 
  is 
  the 
  corvinus 
  or 
  largillierti 
  group 
  of 
  species, 
  

   characterized 
  by 
  medium- 
  to 
  large-sized 
  shells 
  with 
  a 
  generally 
  elongate- 
  

   ovate 
  or 
  elongate-conic 
  outline, 
  rather 
  flat-sided 
  whorls, 
  and 
  almost 
  

   completely 
  smooth 
  macroscopic 
  sculpture. 
  The 
  egg-laying 
  habits 
  are 
  

   quoted 
  above. 
  The 
  Cuban 
  species 
  nigrata 
  Poey 
  1858, 
  fuentesi 
  Aguayo 
  

   1936, 
  and 
  violaceus 
  Preston 
  1911 
  apparently 
  belong 
  here. 
  Synonyms 
  

   of 
  Pachychilus, 
  sensu 
  stricto, 
  include 
  Cercimelania 
  Crosse 
  and 
  Fischer 
  

   (1892, 
  p. 
  327) 
  with 
  P. 
  liehmanni 
  (Philippi) 
  as 
  genotype, 
  and 
  Sphaero- 
  

   melania 
  Rovereto 
  (1899, 
  p. 
  109) 
  with 
  the 
  same 
  genotype 
  as 
  Pachy- 
  

   chilus, 
  since 
  it 
  was 
  proposed 
  as 
  a 
  substitute 
  name. 
  Apparently 
  both 
  

   Crosse 
  and 
  Fischer 
  and 
  Hannibal 
  did 
  not 
  know 
  of 
  Reeve's 
  type 
  desig- 
  

   nation 
  and 
  incorrectly 
  listed 
  P. 
  graphium 
  (Morelet) 
  as 
  the 
  genotype. 
  

  

  Subgenus 
  Glyptomelania 
  Crosse 
  and 
  Fischer, 
  1892 
  

  

  Glyptomelania 
  Crosse 
  and 
  Fischer 
  (1892, 
  p. 
  328) 
  is 
  confined 
  to 
  

   Central 
  America. 
  This 
  group 
  of 
  large 
  shells 
  with 
  variable 
  to 
  nodose 
  or 
  

   subspinose 
  sculpture 
  includes 
  glaphyrus 
  (Morelet), 
  the 
  subgenotype 
  

   by 
  original 
  designation. 
  The 
  eggs 
  of 
  this 
  species 
  have 
  been 
  recorded 
  

   by 
  Goodrich 
  and 
  Van 
  der 
  Schalie 
  as 
  quoted 
  above. 
  

  

  Subgenus 
  Pilsbrychilus 
  Morrison, 
  1952 
  

  

  Pilshrychilus 
  Morrison 
  (1952, 
  p. 
  7) 
  is 
  distinguished 
  from 
  other 
  known 
  

   members 
  of 
  the 
  genus 
  by 
  the 
  markedly 
  sinuous 
  lip-margin 
  developed 
  

   in 
  mature 
  adult 
  shells. 
  It 
  seems 
  probable 
  that 
  examination 
  of 
  the 
  

   animal 
  will 
  serve 
  to 
  corroborate 
  the 
  distinction 
  of 
  this 
  group 
  now 
  based 
  

  

  