﻿Explanation 
  of 
  Plate 
  XXII. 
  

  

  Fig. 
  1. 
  Hydro-ptila 
  sparsa. 
  Head 
  viewed 
  from 
  above 
  showing 
  four 
  

   eversible 
  tubercles 
  partly 
  expanded. 
  Width 
  across 
  eyes 
  

   •6 
  mm. 
  

  

  2. 
  Two 
  of 
  the 
  androconia 
  with 
  their 
  sockets 
  and 
  glands. 
  

  

  Length 
  from 
  bottom 
  of 
  socket 
  to 
  apex 
  of 
  scale 
  -03 
  mm. 
  

  

  3. 
  Enlarged 
  view 
  of 
  one 
  of 
  the 
  tubercles 
  partly 
  expanded. 
  

  

  Width 
  in 
  narrowest 
  part 
  -015 
  mm. 
  

  

  4. 
  Section 
  through 
  one 
  of 
  the 
  lobes. 
  Length 
  -15 
  mm. 
  

  

  5. 
  Part 
  of 
  ditto 
  (not 
  necessarilj' 
  the 
  same 
  section) 
  showing 
  

  

  epithelium 
  and 
  parts 
  of 
  cuticle 
  hairs. 
  Greatest 
  width 
  

   •03 
  mm. 
  

  

  6. 
  Section 
  through 
  head 
  showing 
  one 
  of 
  the 
  tubercles 
  partly 
  

  

  everted. 
  Length 
  of 
  tubercle 
  -18 
  mm. 
  

  

  7. 
  Hydroptila 
  simulans. 
  Head 
  with 
  lobes 
  closed. 
  Width 
  

  

  across 
  eyes 
  -77 
  mm. 
  

  

  8. 
  Section 
  through 
  same 
  in 
  plane 
  of 
  brushes. 
  Width 
  across 
  

  

  eyes 
  -6 
  mm. 
  

  

  9. 
  Part 
  of 
  one 
  of 
  the 
  brush 
  hairs 
  showing 
  structure. 
  Greatest 
  

  

  width 
  -003 
  mm. 
  

   10. 
  Enlarged 
  vieAv 
  of 
  brush 
  bag 
  showing 
  hair 
  sockets 
  and 
  

  

  epithelium. 
  Greatest 
  thickness 
  -015 
  mm. 
  

   H. 
  Hydroptila 
  ocadta. 
  Part 
  of 
  a 
  brush. 
  Length 
  of 
  hairs 
  

  

  •22 
  mm. 
  

  

  12. 
  A 
  small 
  androconium 
  from 
  lobe 
  of 
  same. 
  Length 
  •Ob^ 
  mm. 
  

  

  13. 
  View 
  of 
  inner 
  surface 
  of 
  lobe 
  of 
  same 
  with 
  secondary 
  brush 
  

  

  retracted, 
  scent-scales, 
  etc. 
  Greatest 
  length 
  •IS 
  mm. 
  

  

  14. 
  One 
  of 
  the 
  scales 
  of 
  the 
  secondary 
  brush. 
  Length 
  -06 
  mm. 
  

  

  15. 
  Hydroptila 
  forcipata. 
  Back 
  view 
  of 
  head 
  with 
  expanded 
  

  

  lobe 
  membranes 
  and 
  hair 
  tufts. 
  Width 
  across 
  eyes 
  

   •58 
  mm. 
  

  

  16. 
  One 
  of 
  the 
  lobes 
  viewed 
  from 
  inner 
  side. 
  Length 
  ^176 
  mm. 
  

  

  17. 
  Part 
  of 
  one 
  of 
  the 
  hairs. 
  Diameter 
  of 
  main 
  stalk 
  003 
  mm. 
  

  

  18. 
  Transverse 
  section 
  of 
  same. 
  Diameter 
  over 
  projections 
  

  

  •005 
  mm. 
  

  

  19. 
  Section 
  through 
  one 
  of 
  the 
  lobes 
  showing 
  gland 
  cells 
  at 
  

  

  base. 
  Length 
  from 
  end 
  of 
  membrane 
  to 
  upper 
  corner 
  

   of 
  lobe 
  ^09 
  mm. 
  

  

  