﻿30 
  ON 
  THE 
  NAIADES, 
  

  

  trices 
  situated 
  on 
  the 
  under 
  side 
  of 
  the 
  cardinal 
  tooth 
  ; 
  cavity 
  of 
  the 
  

   beaks 
  obtusely 
  angular 
  ; 
  nacre 
  pearly 
  white 
  and 
  iridescent. 
  

  

  Remarks. 
  — 
  1 
  have 
  had 
  a 
  single 
  specimen 
  of 
  this 
  shell 
  for 
  some 
  years, 
  

   and 
  although 
  satisfied 
  it 
  differed 
  from 
  any 
  described 
  species, 
  I 
  deferred 
  

   bringing 
  it 
  forward 
  until 
  I 
  should 
  have 
  an 
  opportunity 
  of 
  examining 
  

   more. 
  In 
  the 
  fine 
  collection 
  of 
  the 
  Academy 
  of 
  Natural 
  Sciences 
  

   I 
  found 
  a 
  second 
  specimen, 
  which 
  so 
  completely 
  coincided 
  in 
  all 
  its 
  

   characters 
  with 
  mine, 
  that 
  I 
  deemed 
  it 
  unnecessary 
  to 
  hesitate 
  erecting 
  

   it 
  into 
  a 
  species. 
  Both 
  the 
  specimens 
  have 
  that 
  enlargement 
  of 
  the 
  

   inferior 
  portion 
  of 
  the 
  umbonial 
  slope 
  mentioned 
  in 
  the 
  remarks 
  on 
  the 
  

   U. 
  Haysianus 
  herein 
  described, 
  which 
  usually 
  causes 
  a 
  remarkable 
  and 
  

   curious 
  denticulation 
  of 
  the 
  margin, 
  and 
  a 
  poverty 
  of 
  the 
  deposition 
  of 
  

   the 
  nacre 
  in 
  that 
  region. 
  It 
  has, 
  perhaps, 
  a 
  stronger 
  resemblance 
  to 
  

   U. 
  ellipsis 
  (nobis) 
  than 
  to 
  any 
  other 
  species. 
  It 
  is 
  however 
  more 
  

   rotund, 
  more 
  minutely 
  rayed, 
  and 
  less 
  oblique. 
  

  

  Unio 
  subglobosus. 
  Plate 
  II. 
  fig;. 
  3. 
  

  

  »• 
  

  

  Testa 
  subglobosd, 
  subaequilaterali, 
  inflatd 
  et 
  postice 
  subangulatd 
  ; 
  valvulis 
  

   crassis 
  ; 
  natibus 
  prominulis 
  rotundatisque 
  ; 
  dentibus 
  cardinalibus 
  latis 
  striatis- 
  

   que, 
  lateralibus 
  subcurvis 
  ; 
  margaritd 
  subrufd, 
  vel 
  colore 
  caryophylli 
  tinctd. 
  

  

  Shell 
  subglobose, 
  nearly 
  equilateral, 
  inflated, 
  subangular 
  behind 
  ; 
  valves 
  thick 
  ; 
  

   beaks 
  slightly 
  prominent, 
  rounded 
  ; 
  cardinal 
  teeth 
  wide 
  and 
  striated 
  ; 
  lateral 
  teeth 
  

   somewhat 
  curved 
  ; 
  nacre 
  pearly 
  and 
  pink 
  coloured. 
  

  

  Hab. 
  Bayou 
  Teche, 
  Louisiana. 
  W. 
  M. 
  Stewart. 
  

  

  My 
  Cabinet. 
  

   Cabinet 
  of 
  the 
  Academy 
  of 
  Natural 
  Sciences 
  of 
  Philadelphia. 
  

   Cabinet 
  of 
  Mr 
  Stewart. 
  

   Cabinet 
  of 
  William 
  Hyde. 
  

   Cabinet 
  of 
  P. 
  H. 
  Nicklin. 
  

   Diam. 
  1*6, 
  Length 
  2-1, 
  Breadth 
  2-9 
  inches. 
  

  

  Shell 
  subglobose, 
  subequilateral, 
  subangular 
  behind, 
  inflated; 
  sub- 
  

   stance 
  of 
  the 
  shell 
  thick 
  ; 
  umbonial 
  slope 
  carinate 
  ; 
  beaks 
  slightly 
  pro- 
  

  

  