﻿AND 
  OTHER 
  FAMILIES. 
  25 
  

  

  the 
  Ohio, 
  certainly 
  has 
  a 
  different 
  aspect 
  from 
  that 
  of 
  our 
  eastern 
  rivers, 
  

   and 
  might 
  with 
  great 
  propriety 
  be 
  referred 
  to 
  the 
  name 
  which 
  Mr 
  Say 
  

   gave 
  it 
  long 
  since, 
  viz. 
  XI. 
  crassus.* 
  There 
  is 
  another 
  shell, 
  however, 
  

   in 
  the 
  Ohio, 
  which 
  has 
  a 
  stronger 
  resemblance 
  than 
  this, 
  and 
  I 
  believe 
  

   it 
  to 
  be 
  the 
  analogue 
  of 
  the 
  Masmodonta 
  marginata 
  (Say). 
  I 
  have 
  

   examined 
  numerous 
  specimens 
  of 
  this 
  species 
  frequently 
  and 
  attentively? 
  

   but 
  cannot 
  distinguish 
  any 
  difference 
  except 
  in 
  the 
  size, 
  the 
  western 
  

   shell 
  being 
  generally 
  much 
  larger. 
  Of 
  the 
  numerous 
  species 
  and 
  

   genera 
  of 
  the 
  families 
  Lymneana, 
  Melaniana 
  and 
  Peristomiana, 
  I 
  have 
  

   never 
  seen 
  a 
  single 
  species 
  common 
  to 
  both 
  waters. 
  To 
  the 
  genus 
  

   Cyclas 
  I 
  have 
  given 
  but 
  little 
  attention, 
  but 
  believe 
  the 
  same 
  observa- 
  

   tions 
  may 
  be 
  extended 
  to 
  this 
  species. 
  

  

  What 
  an 
  interesting 
  field 
  do 
  these 
  facts 
  spread 
  open 
  to 
  the 
  inquiring 
  

   philosopher! 
  Why 
  should 
  the 
  streams 
  which 
  flow 
  down 
  the 
  sides 
  of 
  

   the 
  same 
  range 
  of 
  mountains, 
  east 
  and 
  west, 
  differ 
  so 
  essentially 
  in 
  

   their 
  productions 
  ? 
  

  

  Let 
  us 
  now 
  examine 
  the 
  extremities 
  of 
  this 
  great 
  chain. 
  To 
  the 
  

   north, 
  where 
  it 
  is 
  lost 
  in 
  the 
  high 
  lands 
  which 
  spread 
  out 
  along 
  the 
  

   southern 
  boundaries 
  of 
  the 
  small 
  lakes 
  in 
  the 
  state 
  of 
  New 
  York, 
  great 
  

   difficulty 
  naturally 
  occurs 
  in 
  defining 
  the 
  line 
  of 
  separation. 
  So 
  far 
  as 
  

   my 
  observation 
  has 
  extended, 
  the 
  shells 
  of 
  the 
  river 
  Mohawk 
  and 
  its 
  

   tributaries 
  are 
  the 
  same 
  with 
  those 
  of 
  the 
  Delaware, 
  Potomac, 
  &c. 
  with 
  

   the 
  exception 
  of 
  a 
  single 
  species 
  Symphynota 
  compressa 
  (nobis), 
  which 
  

   is 
  found 
  near 
  Albany, 
  and 
  which 
  exists 
  also 
  in 
  the 
  Ohio. 
  The 
  tribu- 
  

   taries 
  of 
  the 
  lakes 
  Erie, 
  Michigan, 
  &c, 
  with 
  few 
  exceptions, 
  produce 
  

   the 
  western 
  species, 
  and 
  consequently 
  the 
  lakes 
  do 
  also.f 
  

  

  The 
  great 
  river 
  Niagara, 
  or 
  rather 
  strait 
  connecting 
  the 
  lakes 
  Erie 
  

   and 
  Ontario, 
  furnishes 
  us 
  with 
  the 
  U. 
  triangularis 
  (Barnes), 
  and 
  other 
  

   species, 
  which 
  are 
  so 
  peculiarly 
  characteristic 
  of 
  our 
  western 
  waters. 
  

   Never 
  having 
  visited 
  the 
  shores 
  of 
  lake 
  Ontario, 
  I 
  cannot 
  pronounce 
  on 
  

   its 
  productions. 
  The 
  shells 
  of 
  the 
  river 
  St 
  Lawrence 
  are, 
  I 
  believe, 
  

  

  * 
  A 
  shell 
  which 
  I 
  have 
  always 
  considered 
  as 
  a 
  truncated 
  variety 
  of 
  U. 
  crassus 
  of 
  the 
  Ohio, 
  

   has 
  by 
  this 
  naturalist 
  been 
  made 
  a 
  new 
  species 
  under 
  the 
  name 
  of 
  U. 
  abruptus. 
  

  

  t 
  Since 
  writing 
  the 
  above 
  I 
  have 
  received 
  the 
  U. 
  complanatus 
  (Soland.) 
  from 
  Lac 
  Vaseux, 
  

   which 
  empties 
  into 
  Green 
  Bay; 
  and 
  more 
  recently 
  the 
  same 
  species 
  from 
  lake 
  Champlain. 
  

   The 
  U. 
  nasutus 
  (Say) 
  has 
  been 
  observed 
  in 
  Grand 
  river, 
  which 
  disembogues 
  into 
  lake 
  Erie. 
  

   VOL. 
  V. 
  G 
  

  

  