﻿OLD 
  AND 
  NEW 
  WORLD 
  MELANUNS 
  — 
  MORRISON 
  365 
  

  

  ogist 
  S. 
  E. 
  Meek 
  should 
  be 
  given 
  credit 
  as 
  the 
  first 
  known 
  discoverer 
  

   of 
  the 
  eggs 
  of 
  any 
  member 
  of 
  the 
  family 
  Plem-oceridae. 
  Reporting 
  on 
  

   collections 
  made 
  in 
  1906 
  (Meek, 
  1908, 
  pp. 
  205-206), 
  he 
  says: 
  

  

  Sphaeromelania 
  largillierti 
  Phil. 
  This 
  is 
  the 
  largest 
  and 
  by 
  far 
  the 
  most 
  abundant 
  

   species 
  of 
  shell 
  found 
  in 
  the 
  lake. 
  It 
  is 
  found 
  everywhere 
  along 
  the 
  shore 
  on 
  plants 
  

   and 
  rocks. 
  This 
  species 
  deposits 
  its 
  eggs 
  in 
  January 
  and 
  February. 
  The 
  eggs 
  are 
  

   very 
  large 
  and 
  are 
  usually 
  attached 
  to 
  the 
  under 
  side 
  of 
  rocks. 
  This 
  species 
  is 
  so 
  

   abundant 
  that 
  its 
  large 
  gelatin-like 
  eggs 
  would 
  furnish 
  a 
  considerable 
  amount 
  of 
  

   food 
  for 
  small 
  fishes. 
  It 
  is 
  a 
  very 
  abundant 
  species 
  in 
  Guatemala 
  and 
  San 
  Salvador 
  

   to 
  Central 
  Nicaragua. 
  

  

  Goodrich 
  and 
  Van 
  der 
  Schalie 
  (1937, 
  pp. 
  39, 
  41, 
  42) 
  have 
  recorded 
  and 
  

   described 
  the 
  eggs 
  of 
  three 
  additional 
  species 
  of 
  Pachychilus 
  as 
  follows: 
  

  

  Pachychilus 
  glaphyrus 
  (Morelet) 
  1849. 
  The 
  eggs 
  were 
  found 
  attached 
  to 
  dead 
  

   leaves, 
  which 
  were 
  abundant 
  in 
  the 
  bottom 
  of 
  the 
  arroyo. 
  The 
  leaves 
  were 
  in 
  

   only 
  a 
  few 
  inches 
  of 
  water 
  on 
  a 
  mud-silt 
  bottom 
  near 
  shore. 
  The 
  eggs 
  occur 
  in 
  

   groups 
  of 
  3 
  to 
  5, 
  are 
  round 
  and 
  glassy 
  in 
  appearance, 
  and 
  are 
  irregularly 
  and 
  line- 
  

   arly 
  arranged 
  as 
  a 
  single 
  loosely 
  attached 
  layer. 
  As 
  might 
  be 
  expected 
  in 
  a 
  

   species 
  as 
  large 
  as 
  glaphyrus, 
  the 
  eggs 
  are 
  also 
  large, 
  having 
  a 
  diameter 
  of 
  3.9 
  mm. 
  

   (Arroyo 
  Yalchactila 
  of 
  the 
  Rio 
  de 
  la 
  Pasion, 
  about 
  4 
  mi. 
  S. 
  W. 
  of 
  La 
  Ceiba, 
  Alta 
  

   Vera 
  Paz, 
  Guatemala) 
  .... 
  

  

  Pachychilus 
  corvinus 
  (Morelet) 
  1849. 
  Egg 
  masses 
  of 
  this 
  species 
  were 
  found 
  

   from 
  which 
  the 
  infant 
  shells 
  were 
  emerging. 
  These 
  were 
  smooth, 
  pinkish 
  carnelian, 
  

   translucent, 
  and 
  bluntly 
  rounded 
  at 
  the 
  periphery. 
  The 
  whorls 
  varied 
  from 
  3 
  to 
  

   3H- 
  With 
  growth 
  the 
  shell 
  generally 
  becomes 
  black, 
  even 
  though 
  the 
  adults 
  may 
  

   be 
  of 
  a 
  mahogany 
  or 
  yellowish 
  color 
  on 
  the 
  body 
  whorls 
  .... 
  

  

  Pachychilus 
  pilsbryi 
  Martens 
  1897. 
  Eggs 
  of 
  this 
  species 
  were 
  found 
  on 
  the 
  lower 
  

   surfaces 
  of 
  stones 
  in 
  a 
  current 
  near 
  shore. 
  The 
  egg 
  masses 
  occur 
  as 
  flat 
  layers 
  

   spread 
  out 
  over 
  flat 
  objects. 
  The 
  size 
  of 
  the 
  egg 
  mass 
  varies, 
  the 
  number 
  of 
  eggs 
  

   in 
  some 
  of 
  them 
  observed 
  running 
  from 
  8 
  to 
  20. 
  The 
  eggs 
  themselves 
  are 
  round, 
  

   shotlike, 
  and 
  transparent. 
  The 
  whole 
  mass 
  is 
  held 
  together 
  by 
  a 
  gelatinous 
  

   coating. 
  The 
  average 
  size 
  of 
  the 
  individual 
  eggs 
  is 
  2.8 
  mm. 
  

  

  We 
  are 
  indeed 
  fortmiate 
  in 
  having 
  on 
  record, 
  in 
  the 
  first 
  four 
  species 
  

   so 
  known, 
  the 
  egg-laying 
  characters 
  of 
  three 
  subgenera 
  of 
  the 
  genus 
  

   Pachychilus. 
  

  

  Subgenus 
  Oxymelania 
  Crosse 
  and 
  Fischer, 
  1892 
  

  

  Oxymelania 
  Crosse 
  and 
  Fischer 
  (1892, 
  p. 
  328) 
  possesses 
  the 
  species 
  

   schiedianus 
  Philippi 
  as 
  genotype 
  by 
  original 
  designation. 
  This 
  group 
  

   of 
  small 
  to 
  medium-sized 
  species 
  has 
  been 
  most 
  completely 
  studied 
  

   in 
  the 
  San 
  Luis 
  Potosi 
  region 
  by 
  Pilsbry, 
  following 
  the 
  collections 
  

   made 
  by 
  A. 
  A. 
  Hinkley. 
  In 
  this 
  subgenus, 
  some 
  species 
  of 
  which 
  are 
  

   widely 
  different 
  in 
  height 
  of 
  spire, 
  and 
  thus 
  of 
  shell 
  outline, 
  the 
  single 
  

   general 
  identifying 
  character 
  is 
  the 
  possession 
  or 
  prominence 
  of 
  macro- 
  

   scopic 
  spiral 
  lirations 
  on 
  the 
  adult 
  shell. 
  The 
  egg-laying 
  habits 
  for 
  

   the 
  species 
  pilsbryi 
  Martens 
  are 
  quoted 
  above. 
  The 
  synonyms 
  of 
  

   Oxymelania 
  include 
  Potamanax 
  Pilsbry 
  (1893, 
  p. 
  340), 
  named 
  only 
  a 
  

   few 
  months 
  later, 
  and 
  Lithasiopsis 
  Pilsbry 
  (1910, 
  p. 
  47). 
  In 
  spite 
  of 
  

  

  273553—54 
  2 
  

  

  