﻿ACADEMY 
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  SCIENCES. 
  381 
  

  

  tinctly 
  divided 
  into 
  several 
  segments, 
  as 
  distinct, 
  though 
  not 
  as 
  numerous, 
  as 
  

   those 
  of 
  a 
  myriapod. 
  All 
  insects 
  breathe 
  by 
  means 
  of 
  trachesE, 
  or 
  air 
  passages, 
  

   which, 
  communicating 
  with 
  the 
  air 
  at 
  various 
  points 
  on 
  the 
  outside 
  of 
  the 
  body, 
  

   ramify 
  among 
  the 
  internal 
  organs, 
  limbs, 
  and 
  wings, 
  and 
  act 
  the 
  part 
  of 
  the 
  

   lungs 
  of 
  a 
  vertebrate. 
  All 
  insects 
  are 
  thus 
  air-inhabiting 
  and 
  air-breathing, 
  

   and 
  although 
  some 
  are 
  adapted 
  to 
  live 
  during 
  the 
  greater 
  part 
  of 
  their 
  lives 
  in 
  

   the 
  water, 
  they 
  are 
  compelled, 
  like 
  the 
  cetaceans 
  among 
  the 
  mammalia, 
  to 
  come 
  

   to 
  the 
  surface 
  to 
  breathe. 
  Almost 
  all 
  the 
  Crustacea, 
  on 
  the 
  contrary, 
  breathe, 
  

   like 
  fishes, 
  the 
  air 
  contained 
  in 
  the 
  water, 
  by 
  means 
  of 
  some 
  modification 
  of 
  

   branchiae 
  or 
  gills 
  ; 
  and 
  although 
  some 
  of 
  them 
  live 
  on 
  the 
  land 
  during 
  the 
  greater 
  

   part 
  or 
  the 
  whole 
  of 
  their 
  lives, 
  they 
  are 
  compelled 
  to 
  choose 
  damp 
  situations, 
  

   so 
  that 
  their 
  branchiae 
  may 
  be 
  kept 
  moist, 
  and 
  thus 
  be 
  enabled 
  to 
  continue 
  their 
  

   functions. 
  

  

  All 
  insects 
  pass 
  through 
  a 
  more 
  or 
  less 
  complete 
  series 
  of 
  metamorphoses, 
  the 
  

   three 
  most 
  conspicuous 
  stages 
  of 
  which 
  have 
  received 
  the 
  names 
  of 
  larva, 
  or 
  

   caterpillar, 
  jJM/Jrt, 
  or 
  chrysalis, 
  and 
  imago, 
  or 
  perfect 
  insect. 
  All 
  the 
  crustaceans 
  

   change 
  their 
  form 
  somewhat 
  before 
  arriving 
  at 
  maturity 
  ; 
  but 
  it 
  is 
  only 
  in 
  the 
  

   higher 
  groups 
  that 
  these 
  are 
  sufficiently 
  marked 
  to 
  entitle 
  them 
  to 
  the 
  name 
  of 
  

   metamorphoses. 
  But 
  there 
  is 
  this 
  difference 
  between 
  the 
  metamorphoses 
  of 
  the 
  

   insect 
  and 
  those 
  of 
  the 
  crustacean 
  : 
  the 
  insect, 
  whether 
  its 
  metamorphoses 
  be 
  

   complete, 
  as 
  in 
  the 
  butterfly, 
  or 
  partial, 
  as 
  in 
  the 
  cricket, 
  attains 
  its 
  full 
  size 
  

   before 
  assuming 
  its 
  imago 
  state 
  ; 
  indeed, 
  the 
  caterpillar 
  is 
  generally 
  much 
  

   larger 
  than 
  the 
  imago. 
  The 
  crustacean, 
  on 
  the 
  other 
  hand, 
  passes 
  through 
  all 
  

   its 
  incomplete 
  stages 
  while 
  still 
  very 
  small, 
  assumes 
  its 
  perfect 
  form, 
  and, 
  as 
  it 
  

   grows, 
  throws 
  off 
  its 
  external 
  hard 
  skeleton 
  and 
  secretes 
  another 
  fitted 
  to 
  its 
  

   increased 
  bulk. 
  

  

  As 
  late 
  as 
  the 
  year 
  1838, 
  Milne 
  Edwards, 
  in 
  his 
  "Natural 
  History 
  of 
  the 
  

   Crustaceans," 
  wrote 
  : 
  " 
  We 
  are 
  not 
  acquainted 
  with 
  any 
  crustacean 
  from 
  the 
  

   western 
  coast 
  of 
  North 
  America." 
  James 
  D. 
  Dana, 
  in 
  his 
  " 
  Crustacea 
  of 
  the 
  

   United 
  States 
  Exploring 
  Expedition," 
  de3cribes 
  several 
  species 
  found 
  between 
  

   San 
  Francisco 
  and 
  Puget 
  Sound. 
  J. 
  W. 
  Randall, 
  De 
  Saussure, 
  and 
  other 
  

   zoologists, 
  also 
  described 
  other 
  species. 
  

  

  The 
  late 
  Wm. 
  Stimpson, 
  in 
  an 
  article 
  published 
  in 
  the 
  "Boston 
  Journal 
  of 
  

   Natural 
  History," 
  1857, 
  describes 
  many 
  new 
  kinds, 
  and 
  catalogues 
  a 
  total 
  of 
  

   one 
  hundred 
  and 
  thifty 
  species 
  belonging 
  to, 
  and 
  peculiar 
  to, 
  the 
  Pacific 
  Coast. 
  

   Stimpson, 
  like 
  his 
  predecessor 
  Dana, 
  did 
  not 
  explore 
  south 
  of 
  San 
  Francisco. 
  

   Since 
  his 
  day 
  no 
  one 
  appears 
  to 
  have 
  given 
  any 
  connected 
  attention 
  to 
  the 
  sub- 
  

   ject 
  ; 
  and 
  when 
  we 
  consider 
  that 
  the 
  unexplored 
  portion 
  extends 
  through 
  Lower 
  

   California, 
  Sonora, 
  Mexico, 
  and 
  Central 
  America, 
  as 
  far 
  south 
  as 
  the 
  Isthmus 
  

   of 
  Panama,, 
  through 
  a 
  region 
  tropical 
  or 
  sub-tropical 
  in 
  climate, 
  and 
  teeming 
  

   with 
  life 
  of 
  every 
  kind, 
  we 
  shall, 
  I 
  think, 
  fully 
  endorse 
  Stimpson's 
  opinion, 
  

   when 
  he 
  says, 
  " 
  We 
  cannot 
  suppose 
  this 
  number 
  to 
  be 
  more 
  than 
  a 
  fourth 
  part 
  

   of 
  that 
  which 
  will 
  be 
  reached 
  when 
  a 
  thorough 
  search 
  shall 
  be 
  instituted." 
  

  

  Ninety-six 
  of 
  the 
  species 
  enumerated 
  by 
  Stimpson 
  belong 
  to 
  the 
  highest 
  

   division 
  of 
  the 
  class, 
  viz 
  : 
  the 
  Podopthabnia, 
  or 
  stalked-eyed 
  crustaceans 
  ; 
  and 
  

  

  