﻿240 
  Panama 
  Shells. 
  

  

  INTRODUCTION. 
  

  

  Mazatlan 
  ; 
  Dec. 
  21 
  to 
  Dec. 
  27 
  at 
  San 
  Bias 
  ; 
  Jan. 
  8, 
  1838 
  to 
  

   Jan. 
  23 
  at 
  Acapulco 
  ; 
  May 
  10 
  to 
  June 
  1 
  at 
  Callao 
  ; 
  June 
  5 
  to 
  

   June 
  17 
  at 
  Payta 
  ; 
  June 
  23 
  to 
  July 
  3 
  at 
  the 
  Gailapagos. 
  The 
  

   Atlas 
  de 
  Zoologie 
  of 
  this 
  expedition, 
  (pub. 
  1846) 
  contained 
  24 
  

   folio 
  plates, 
  of 
  shells 
  and 
  mollusca. 
  The 
  text 
  we 
  have 
  not 
  

   seen. 
  

  

  In 
  1839 
  the 
  U. 
  S. 
  Exploring 
  Expedition 
  touched 
  at 
  Callao, 
  

   which 
  was 
  the 
  only 
  place 
  in 
  this 
  zoological 
  province, 
  that 
  was 
  

   visited 
  by 
  the 
  expedition. 
  About 
  30 
  species 
  of 
  shells 
  were 
  

   collected, 
  of 
  which 
  four 
  new 
  species 
  have 
  been 
  described 
  by 
  

   Dr. 
  G-ould 
  in 
  the 
  Proceedings 
  of 
  the 
  Boston 
  Society 
  of 
  Natural 
  

   History 
  since 
  1846. 
  

  

  In 
  the 
  Zeitschrift 
  fur 
  Malakologie 
  of 
  Aug. 
  1847, 
  Dr. 
  K. 
  

   T. 
  Menke 
  commenced 
  a 
  catalogue, 
  with 
  descriptions 
  of 
  the 
  

   new 
  species, 
  of 
  the 
  shells 
  of 
  Mazatlan. 
  These 
  shells 
  were 
  

   collected 
  by 
  Mr. 
  Henry 
  Melchers 
  of 
  Bremen, 
  who 
  has 
  spent 
  

   several 
  years 
  in 
  Mazatlan. 
  Additions 
  have 
  since 
  been 
  made 
  

   to 
  the 
  catalogue, 
  and 
  up 
  to 
  Feb. 
  (inc.) 
  1851, 
  Dr. 
  Menke 
  has 
  

   catalogued 
  173 
  Mazatlan 
  species. 
  Of 
  these 
  26 
  are 
  described 
  

   as 
  new 
  species, 
  not 
  including 
  a 
  few 
  which 
  were 
  proposed 
  as 
  

   new 
  but 
  have 
  since 
  been 
  identified 
  by 
  Dr. 
  Menke 
  v/ith 
  pre- 
  

   viously 
  described 
  species. 
  

  

  At 
  the 
  present 
  time 
  Dr. 
  Gould 
  is 
  engaged 
  in 
  the 
  exami- 
  

   nation 
  of 
  species, 
  which 
  have 
  been 
  collected 
  at 
  various 
  points 
  

   between 
  San 
  Francisco 
  and 
  Mazatlan. 
  These 
  collections 
  were 
  

   made 
  by 
  Maj. 
  William 
  Rich, 
  and 
  Col. 
  E. 
  Jewett, 
  U. 
  S, 
  A.^ 
  

   and 
  by 
  Lieut. 
  Thomas 
  P. 
  Green, 
  U. 
  S. 
  N. 
  They 
  are 
  the 
  more 
  

   important, 
  because 
  Ihey 
  come 
  from 
  regions 
  intermediate 
  be- 
  

   tween 
  two 
  great 
  zoological 
  provinces, 
  and 
  we 
  may 
  hope 
  there- 
  

   fore 
  that 
  Dr. 
  Gould 
  will 
  show, 
  with 
  as 
  much 
  precision 
  as 
  the 
  

   facts 
  themselves 
  will 
  admit, 
  the 
  boundary 
  between 
  them. 
  At 
  

   a 
  meeting 
  of 
  the 
  Boston 
  Society 
  of 
  Natural 
  History, 
  Septem- 
  

   ber 
  3, 
  1851, 
  Dr. 
  Gould 
  read 
  descriptions 
  of 
  17 
  new 
  species 
  of 
  

   Acephala 
  from 
  these 
  frontier 
  regions. 
  The 
  collections 
  mada 
  

  

  