﻿218 
  Descriptions 
  of 
  Species 
  of 
  Fresh 
  Water 
  Shells. 
  

  

  the 
  inner 
  web. 
  The 
  outer 
  edges 
  of 
  all, 
  delicately 
  margined 
  

   with 
  dull 
  white, 
  

  

  3d 
  qaill 
  longest, 
  then, 
  in 
  succession, 
  2d, 
  4th, 
  5th 
  and 
  6th. 
  

   Length 
  5j 
  ; 
  extent 
  8| 
  ; 
  wing 
  from 
  carpal 
  joint 
  2]§ 
  ; 
  bill 
  

   along 
  ridge 
  f 
  g^, 
  rictus 
  ff 
  ; 
  tarsus 
  ^ 
  ; 
  hind 
  toe 
  and 
  claw 
  |^ 
  ; 
  

   middle 
  do. 
  |§. 
  

  

  This 
  species, 
  which 
  was 
  shot 
  near 
  Cleveland, 
  Ohio, 
  by 
  Mr. 
  

   Charles 
  Pease, 
  May 
  13th, 
  1851, 
  is 
  appropriately 
  dedicated 
  to 
  

   Dr. 
  Jared 
  P. 
  Kirtland, 
  of 
  Cleveland, 
  a 
  gentleman 
  to 
  whom, 
  

   more 
  than 
  any 
  one 
  living, 
  we 
  are 
  indebted 
  for 
  a 
  knowledge 
  of 
  

   the 
  Natural 
  History 
  of 
  the 
  Mississippi 
  Valley. 
  

  

  Descriptions 
  of 
  Two 
  New 
  Species 
  of 
  Fresh 
  Water 
  Shells. 
  

   By 
  Temple 
  Prime, 
  Corresponding 
  Member. 
  Read 
  26th 
  

   January, 
  1852. 
  

  

  Cyclas 
  Securis. 
  Plate 
  VI. 
  

  

  C. 
  testa, 
  parva, 
  rhomboidea, 
  postice 
  abruptissima, 
  sube- 
  

   quilaterali 
  ; 
  natibus 
  elevatissimis 
  ; 
  dentibus 
  cardinalibus 
  

   minutis, 
  lateralibus 
  elongatis, 
  fortibus. 
  

  

  Long. 
  0.27; 
  Lat. 
  0.24 
  ; 
  Diam. 
  0.16. 
  

  

  Shell 
  small, 
  rhomboid, 
  posteriorily 
  very 
  abrupt, 
  somewhat 
  

   equilateral, 
  striations 
  hardly 
  visible, 
  color 
  light, 
  pale 
  yellow 
  ; 
  

   beaks 
  very 
  prominent. 
  Hab. 
  Massachusetts. 
  

  

  This 
  is 
  one 
  of 
  our 
  best 
  distinguished 
  and 
  most 
  attractive 
  

   species 
  : 
  it 
  somewhat 
  resembles 
  the 
  Cyclas 
  truncata 
  of 
  Lins- 
  

   ley, 
  but 
  is 
  much 
  more 
  compressed, 
  and 
  is 
  less 
  acute. 
  One 
  of 
  its 
  

   best 
  marks 
  is 
  the 
  contrast 
  of 
  the 
  roundness 
  of 
  its 
  anterior 
  

   with 
  the 
  abruptness 
  of 
  its 
  posterior. 
  When 
  the 
  animal 
  is 
  

   alive, 
  this 
  shell 
  assumes 
  a 
  bright 
  pink 
  color 
  ; 
  and 
  its 
  beaks 
  

   are 
  of 
  a 
  dark 
  brown 
  ; 
  it, 
  however, 
  loses 
  these 
  peculiarities 
  

   when 
  the 
  animal 
  is 
  dried 
  up. 
  

  

  