﻿Explanation 
  of 
  Plate 
  II. 
  

  

  Fig. 
  1. 
  Diagram 
  of 
  the 
  proximal 
  portion 
  of 
  an 
  ommatidium 
  x 
  1200. 
  

   bm. 
  Basal 
  membrane. 
  

   n. 
  Nerve. 
  

  

  nc. 
  Nucleated 
  nerve 
  cell. 
  

   t. 
  Main 
  tracheal 
  tube. 
  

   tt. 
  Tracheal 
  branches. 
  

   ret. 
  Retinula. 
  

   r. 
  Rhabdom. 
  

   tf. 
  Tracheal 
  distributor. 
  

  

  2. 
  An 
  ommatidium 
  and 
  cone 
  of 
  V. 
  iirticae 
  to 
  show 
  the 
  relative 
  

  

  size 
  of 
  the 
  parts 
  x 
  350. 
  

   cc. 
  Crystalline 
  cone. 
  

   r. 
  Rhabdom. 
  

   tf. 
  Tracheal 
  distributor. 
  

  

  3. 
  Transverse 
  section 
  of 
  periopticon 
  showing 
  regular 
  arrange- 
  

  

  ments 
  of 
  the 
  nerve 
  bundles 
  x 
  1350. 
  

  

  4. 
  Transverse 
  section 
  of 
  nerve 
  bundles, 
  nucleated 
  cells, 
  and 
  

  

  tracheae 
  just 
  below 
  basal 
  membrane 
  x 
  1350. 
  

   n. 
  Nerves. 
  

   t. 
  Tracheal 
  tube. 
  

  

  5. 
  Transverse 
  section 
  of 
  tracheal 
  distributor 
  x 
  1350. 
  

  

  n. 
  Nerves 
  (retinulae). 
  

   c. 
  Cruciform 
  chitinous 
  body 
  in 
  distributor. 
  

   ts. 
  Tracheal 
  spaces. 
  

   (j. 
  Transverse 
  section 
  of 
  ommatidia 
  above 
  tracheal 
  distributor 
  

   X 
  1350. 
  

   tt. 
  Tracheal 
  branches. 
  

   r. 
  Rhabdom. 
  

   ret. 
  Retinula. 
  

  

  7. 
  Diagram 
  of 
  a 
  lens 
  cylinder 
  of 
  its 
  own 
  focal 
  length. 
  

  

  8. 
  Diagram 
  of 
  a 
  lens 
  cylinder 
  of 
  twice 
  its 
  own 
  focal 
  length. 
  

  

  