﻿120 
  

  

  DAVID 
  MILLER. 
  

  

  (fig. 
  12), 
  on 
  the 
  opposite 
  side 
  to 
  which, 
  near 
  the 
  base 
  of 
  the 
  siphon, 
  is 
  a 
  single 
  spine 
  

   (fig. 
  11). 
  Orifice 
  of 
  siphon 
  closed 
  externally 
  by 
  a 
  pair 
  of 
  cup-shaped 
  valves, 
  from 
  

   each 
  of 
  which 
  arises 
  a 
  tuft 
  and 
  a 
  single 
  hair 
  ; 
  on 
  the 
  siphon 
  near 
  the 
  orifice 
  is 
  a 
  bristle- 
  

   like 
  hair 
  and 
  two 
  very 
  long 
  and 
  delicate 
  branched 
  ones 
  ; 
  internally 
  the 
  two 
  tracheae 
  

  

  Fig. 
  12. 
  Siphon 
  of 
  larva. 
  

  

  do 
  not 
  reach 
  the 
  external 
  valves, 
  each 
  tracheal 
  opening 
  being 
  protected 
  by 
  a 
  cup- 
  

   shaped 
  valve, 
  one 
  being 
  opposed 
  to 
  the 
  other, 
  so 
  that 
  when 
  drawn 
  together 
  their 
  rims 
  

   meet 
  and 
  completely 
  close 
  the 
  tracheae 
  (fig. 
  12). 
  Along 
  the 
  lower 
  inner 
  edge 
  of 
  each 
  

   valve 
  where 
  attached 
  to 
  the 
  trachea 
  is 
  a 
  ridge 
  bearing 
  numerous 
  short 
  and 
  delicate 
  

   hairs 
  (fig. 
  13). 
  

  

  Fig. 
  13. 
  An 
  internal 
  tracheal 
  

   valve 
  of 
  larva. 
  

  

  Anal 
  plate 
  confined 
  to 
  the 
  distal 
  two-thirds 
  of 
  the 
  anal 
  segment 
  and 
  extending 
  

   on 
  each 
  side 
  to 
  the 
  median 
  line 
  (fig. 
  11) 
  ; 
  an 
  inconspicuous 
  bristle 
  arises 
  from 
  anal 
  

   plate 
  on 
  one 
  side. 
  Hair-tufts 
  on 
  dorsal 
  angle 
  of 
  anal 
  segment 
  consisting 
  of 
  a 
  pair 
  

   of 
  long 
  straight 
  hairs 
  and 
  a 
  single 
  tuft 
  of 
  somewhat 
  shorter 
  ones. 
  Anal 
  sills 
  absent 
  

   and 
  represented 
  by 
  three 
  short 
  tubercles 
  capable 
  of 
  being 
  retracted 
  (fig. 
  11). 
  Ventral 
  

   fringe 
  well 
  developed, 
  consisting 
  of 
  several 
  tufts 
  of 
  very 
  long 
  hairs. 
  

  

  Comb 
  of 
  eighth 
  segment 
  triangular, 
  the 
  spines 
  strong 
  and 
  stout, 
  those 
  at 
  the 
  apex 
  

   large 
  and 
  conspicuous 
  but 
  very 
  short 
  at 
  the 
  base 
  ; 
  the 
  vestiture 
  of 
  this 
  segment 
  as 
  

   in 
  accompanying 
  diagram 
  (fig. 
  11). 
  

  

  Head 
  pendulous, 
  transversely 
  ovate 
  from 
  above, 
  narrower 
  than 
  the 
  thorax, 
  

   opaque 
  ; 
  mouth-brushes 
  golden. 
  Antennae 
  apparently 
  single- 
  jointed, 
  bare, 
  except 
  

   for 
  the 
  short 
  terminal 
  hairs 
  (fig. 
  14). 
  Clypeus 
  slightly 
  sinuated 
  and 
  armed 
  with 
  a 
  

   pair 
  of 
  straight 
  spines. 
  Labrum 
  cuneiform, 
  its 
  apex 
  extending 
  beyond 
  the 
  chitinous 
  

   processes 
  of 
  the 
  mouth-brushes 
  ; 
  its 
  surface 
  clothed 
  with 
  bristle-like 
  hairs, 
  while 
  

   near 
  its 
  base 
  in 
  front 
  of 
  the 
  clypeus 
  is 
  a 
  small 
  hair-tuft 
  ; 
  at 
  the 
  apex 
  dorsally 
  is 
  a 
  

  

  