﻿ANATOMY 
  OF 
  THE 
  WESTERN 
  CRICKET. 
  177 
  

  

  phageal 
  ganglia, 
  there 
  are 
  three 
  thoracic 
  ganglia, 
  the 
  last 
  one 
  being 
  sit- 
  

   uated 
  opposite 
  the 
  insertion 
  of 
  the 
  third 
  pair 
  of 
  legs. 
  There 
  are 
  six 
  ab- 
  

   dominal 
  ganglia, 
  the 
  sixth 
  and 
  last 
  one 
  being 
  the 
  largest 
  ; 
  the 
  first 
  one 
  

   is 
  situated 
  quite 
  near 
  the 
  last 
  thoracic. 
  

  

  The 
  sympathetic 
  nerve 
  (Fig. 
  5, 
  sm) 
  is 
  composed 
  of 
  two 
  branches, 
  which 
  

   arise 
  from 
  the 
  under 
  side 
  of 
  the 
  oesophagus, 
  and 
  extend 
  back 
  to 
  the 
  end 
  

   of 
  the 
  crop 
  (ingluvies) 
  next 
  to 
  the 
  proventricle, 
  where 
  two 
  minute 
  ganglia 
  

   are 
  situated, 
  one 
  on 
  each 
  side. 
  There 
  are 
  three 
  small 
  sympathetic 
  

   ganglia 
  under 
  and 
  near 
  the 
  brain, 
  the 
  anterior 
  one 
  being 
  called 
  the 
  

   frontal 
  ganglion 
  (Fig. 
  o,/#). 
  

  

  The 
  breathing 
  apparatus 
  consists, 
  in 
  insects, 
  of 
  air-tubes, 
  called 
  tracheae 
  

   which 
  originate 
  at 
  the 
  breathing 
  pores 
  (spiracles), 
  and 
  ramify 
  through- 
  

   out 
  the 
  interior 
  of 
  the 
  body, 
  and 
  thus 
  carry 
  the 
  air 
  into 
  every 
  part 
  of 
  

   the 
  body; 
  thus 
  everywhere 
  coming 
  in 
  contact 
  with 
  the 
  blood, 
  which 
  

   flows 
  freely 
  into 
  all 
  the 
  interstices 
  of 
  the 
  body, 
  among 
  the 
  viscera 
  and 
  

   muscles, 
  not 
  being 
  contained 
  in 
  arteries 
  and 
  veins. 
  

  

  There 
  are 
  two 
  kinds 
  of 
  tracheae 
  in 
  the 
  Anabrus, 
  those 
  which 
  are 
  simple, 
  

   and 
  those 
  which 
  are 
  dilated, 
  but 
  there 
  are 
  no 
  air 
  vesicles 
  or 
  sacs, 
  such 
  as 
  

   exist 
  in 
  the 
  locust 
  and 
  other 
  flying 
  insects 
  ; 
  so 
  far 
  as 
  is 
  known 
  no 
  larval 
  

   or 
  creeping, 
  unwinged 
  insects 
  possess 
  air-sacs, 
  and 
  we 
  see 
  that 
  in 
  an 
  

   insect 
  like 
  the 
  Anabrus, 
  when 
  the 
  wings 
  are 
  but 
  partially 
  developed, 
  but 
  

   not 
  used 
  to 
  fly 
  with, 
  they 
  are 
  not 
  present. 
  

  

  The 
  tracheae 
  of 
  Anabrus 
  purpurascens 
  are 
  small 
  where 
  they 
  arise 
  from 
  

   the 
  spiracles, 
  but 
  certain 
  of 
  the 
  branches 
  after 
  leaving 
  the 
  small 
  spiracu- 
  

   lar 
  opening 
  are 
  dilated. 
  There 
  are 
  eight 
  sets 
  of 
  dilated 
  tracheae 
  in 
  the 
  

   abdomen 
  ; 
  the 
  anterior 
  ones 
  are 
  imbedded 
  in 
  the 
  muscles 
  of 
  the 
  sides 
  of 
  

   the 
  body. 
  The 
  fifth 
  set 
  of 
  abdominal 
  dilated 
  tracheae 
  supply 
  the 
  ovaries, 
  

   there 
  being 
  about 
  40 
  branches 
  distributed 
  among 
  the 
  tubes, 
  one 
  for 
  each 
  

   of 
  the 
  ovarian 
  tubes. 
  The 
  sixth 
  set 
  send 
  branches 
  to 
  the 
  stomach, 
  

   which 
  is 
  provided 
  with 
  eight 
  large 
  dilated 
  tracheae, 
  four 
  on 
  a 
  side, 
  

   by 
  which 
  the 
  organ 
  is 
  held 
  loosely 
  in 
  place. 
  No 
  tracheae 
  are 
  apparently 
  

   sent 
  to 
  the 
  ingluvies 
  or 
  crop. 
  The 
  seventh 
  set 
  of 
  abdominal 
  tracheae 
  

   distribute 
  their 
  branches 
  to 
  the 
  intestine, 
  a 
  pair 
  of 
  these 
  being 
  large 
  

   long, 
  sinuous, 
  dilated 
  tracheae. 
  The 
  tracheae 
  branching 
  from 
  the 
  eighth 
  

   (and 
  last) 
  pair 
  of 
  abdominal 
  spiracles 
  supply 
  the 
  rectum, 
  and 
  a 
  pair 
  of 
  

   dilated 
  tracheae 
  are 
  very 
  large, 
  forming 
  a 
  barrel 
  or 
  spindle-shaped 
  sac, 
  

   situated 
  on 
  each 
  side 
  of 
  the 
  rectum 
  just 
  within 
  the 
  anus. 
  These 
  two 
  

   large 
  sac-like 
  tracheae 
  might 
  at 
  first 
  sight 
  be 
  mistaken 
  for 
  true 
  air-sacs, 
  

   but 
  they 
  have 
  the 
  same 
  structure 
  apparently 
  under 
  the 
  microscope 
  as 
  

   the 
  tracheae 
  themselves, 
  the 
  spiral 
  thread 
  being 
  well 
  developed. 
  

  

  On 
  the 
  lower 
  side 
  of 
  the 
  abdomen, 
  under 
  the 
  digestive 
  canal, 
  may 
  be 
  

   found 
  the 
  two 
  main 
  longitudinal 
  (stigmatal) 
  tracheae 
  corresponding 
  to 
  

   the 
  two 
  stigmatal 
  tracheae 
  of 
  Caloptenus. 
  216 
  They 
  lie 
  one 
  on 
  each 
  side 
  

   of 
  the 
  nervous 
  cord, 
  and 
  are 
  supplied 
  with 
  horizontal 
  branches 
  from 
  the 
  

   spiracles, 
  and 
  the 
  pair 
  extend 
  into 
  the 
  head. 
  

  

  '^Compare 
  the 
  deseription 
  and 
  Figs. 
  16 
  and 
  17 
  8, 
  p. 
  268, 
  First 
  Report 
  of 
  the 
  U. 
  s! 
  Entomological 
  Com-, 
  

   mission, 
  1878. 
  

  

  12 
  L 
  

  

  