﻿ODONATA. 
  

  

  329 
  

  

  (uropleurites) 
  are 
  only 
  seen 
  from 
  beneath, 
  but 
  are 
  well 
  developed, 
  

   abdomen 
  of 
  Termes 
  Jlavvpes 
  is 
  substantially 
  as 
  in 
  Termopsis. 
  

  

  The 
  

  

  Fig. 
  13.— 
  Abdomen 
  of 
  Termes 
  flavipes. 
  Lettering 
  as 
  in 
  fig. 
  12. 
  Enlarged. 
  

  

  Suborder 
  2. 
  Odonata. 
  Plates 
  XLVII-L. 
  

  

  THE 
  HEAD. 
  

  

  Agrion 
  verticale 
  Say. 
  (PI. 
  XLYII, 
  figs. 
  4-6.) 
  The 
  structure 
  of 
  the 
  

   head 
  of 
  Agrion 
  and 
  Oalopteryx 
  is 
  more 
  easily 
  understood 
  than 
  that 
  of 
  

   ^schna 
  and 
  Libellula, 
  as 
  their 
  eyes 
  are 
  much 
  smaller, 
  and 
  the 
  develop- 
  

   ment 
  of 
  the 
  epicranium 
  is 
  more 
  equable 
  and 
  normal. 
  The 
  head 
  is 
  unusu- 
  

   ally 
  short 
  and 
  widej 
  the 
  orbits 
  very 
  wide; 
  eyes 
  spherical. 
  The 
  epicra- 
  

   nium, 
  exclusive 
  of 
  the 
  orbits, 
  is 
  about 
  as 
  long 
  as 
  broad, 
  with 
  a 
  decided 
  

   ocellar 
  area, 
  the 
  ocelli 
  being 
  large 
  and 
  closel^^ 
  contiguous. 
  In 
  front 
  of 
  

   the 
  ocelli 
  is 
  a 
  deep 
  impressed 
  line 
  parallel 
  to 
  the 
  clypeus. 
  

  

  The 
  clypeus 
  is 
  moderately 
  large, 
  about 
  one-half 
  as 
  long 
  as 
  broad, 
  

   with 
  a 
  high, 
  sharp, 
  shelf-like 
  side; 
  it 
  is 
  divided 
  into 
  a 
  clj^peus 
  posterior 
  

   and 
  anterior; 
  the 
  post-clypeus 
  being 
  horizontal 
  like 
  a 
  shelf, 
  and 
  the 
  

   anteclypeus 
  forming 
  a 
  vertical 
  wall. 
  

  

  The 
  labrum 
  is 
  large 
  and 
  broad, 
  well 
  rounded 
  in 
  front. 
  The 
  genae 
  are 
  

   very 
  large 
  and 
  broad, 
  smooth, 
  and 
  continuous 
  with 
  the 
  orbits. 
  The 
  

   gula 
  is 
  membranous. 
  

  

  In 
  Calopteryx 
  ^naculata 
  the 
  head 
  is 
  much 
  as 
  in 
  Agrion, 
  but 
  the 
  clypeus 
  

   is 
  more 
  clearly 
  defined 
  and 
  seiDarate 
  from 
  the 
  epicranium 
  than 
  in 
  Agrion. 
  

   The 
  epicranium 
  is 
  wider 
  and 
  larger 
  than 
  in 
  Agrion; 
  a 
  transverse 
  im- 
  

   pressed 
  line 
  separates 
  it 
  into 
  a 
  posterior 
  and 
  anterior 
  area. 
  

  

  In 
  Mschna 
  heros 
  (PI. 
  XLYII, 
  figs. 
  1-3) 
  there 
  is 
  no 
  definite 
  trace 
  of 
  the 
  

   occiput, 
  unless 
  a 
  postorbital 
  ridge 
  bet^^een 
  the 
  gula 
  and 
  orbits 
  marks 
  

   its 
  limits. 
  This 
  ridge 
  becomes 
  obsolete 
  towards 
  the 
  median 
  line 
  near 
  the 
  

  

  