MR.  J.  O.  WESTWOOD  ON  NYCTERIBIA. 
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mediate  legs  the  corresponding  process  is  also  detached,  being  affixed  to  the  internally 
elongated  trochanter  at  its  base :  it  is  horny,  lunate,  and  very  small,  and  externally 
armed  with  about  sixteen  obtuse  teeth,  directed  upwards  and  backwards.  This  organ 
was  first  noticed  by  Hermann,  by  whom  it  was  figured.  Mr.  Curtis  thus  describes 
it:  "Wings  none,  but  there  is  a  narrow  appendage  ciliated  with  short  strong  bristles, 
on  each  side  at  the  base  of  the  middle  pair  of  legs adding,  that  these  ciliated  ap- 
pendages "  may  cover  spiracles  for  breathing,  organs  for  hearing,  or  they  may  be  the 
analogue  of  rudimentary  wings."  That  the  latter  of  these  suppositions  is  correct,  I 
feel  induced  to  conceive,  notwithstanding  their  extraordinary  form  and  our  ignorance 
of  their  uses,  from  their  situation  and  evident  attachment  to  the  internal  base  of  the 
intermediate  legs.  The  supposition  that  they  are  organs  of  hearing  seems  to  have 
arisen  from  the  supposed  want  of  antenna,  and  cannot  therefore  be  maintained,  as  those 
organs  exist ;  while  the  idea  that  they  may  be  connected  with  spiracles  for  breathing 
requires  more  notice,  from  having  been  entertained  both  by  Latreille  and  M.  Dufour,  the 
latter  of  whom  has  entered  at  some  length  into  the  reasons  which  have  induced  him  to 
adopt  such  idea:  these  consist,  1.  in  the  position  of  this  pectinated  organ;  2.  in  the 
asserted  absence  of  any  other  point  which  might  be  considered  as  a  respiratory  orifice  ; 
and  3.  in  the  evident  analogy  between  Nycteribia  and  the  Hippoboscidee.  Now  although 
the  first  of  these  reasons  is  certainly  in  favour  of  such  opinion,  the  latter  two  are  in- 
correct, the  abdomen,  as  will  subsequently  be  described,  being  furnished  with  a  series 
of  spiracles,  and  the  thorax  itself  exhibiting  a  pair  of  minute  oval  points,  which  appear 
to  me  to  be  evidently  spiracles,  and  which  exist  in  the  elevated  crustaceous  ridge  be- 
tween the  central  and  anterior  lateral  portions  of  the  thorax,  immediately  behind  the 
insertion  of  the  head,  which  organs  I  have  noticed  not  only  in  Colonel  Sykes's 
insects,  but  also  in  my  Chinese  species.  As  to  the  analogy  existing  between  Nyc- 
teribia and  the  Hippoboscidce,  it  is  to  be  observed,  that  from  the  totally  distinct  organi- 
zation of  the  thorax  it  is  difficult  to  trace  the  situation  in  Nycteribia  which  is  analogous 
to  the  position  of  the  spiracles  in  the  Hippoboscida.  These,  it  is  to  be  observed,  vary 
in  their  location  ;  but  in  none  are  the  anterior  pair  placed  between  the  anterior  and  in- 
termediate legs,  as  are  the  pectinated  processes  in  Nycteribia,  but,  on  the  contrary,  in 
a  higher  and  more  dorsal  position,  which  would  probably  occur  in  Nycteribia  nearer 
the  base  of  the  head^ 
The  legs  offer  several  remarkable  peculiarities :  they  are  very  long  and  strong,  and 
'  M.  Dufour  has  proposed  the  employment  of  the  position  and  structure  of  the  spiracles  as  affording  cha- 
racters, "  aussi  solides  que  faciles  a  explorer,"  for  the  establishment  of  families  and  genera,  and  has  given  an 
account  of  their  structure  in  the  Pupipara.  That  they  would  afford  solid  characters  cannot  be  questioned ; 
but  some  notion  may  be  obtained  of  the  difficulty  attending  their  adoption,  when  it  is  stated  that  M.  Dufour 
has  overlooked  the  entire  series  of  abdominal  spiracles  of  the  Hippohoscidce.  See  Lyonnet's  Posthumous  Re- 
searches, pi.  1.  f.  2.  &  3. 
