278 
MR.  J.  O.  WESTWOOD  ON  NYCTERIBIA. 
In  all  the  three  individuals  under  examination,  on  each  side  of  the  head,  near  the 
anterior  angles,  an  eye  is  placed,  composed  of  two  small  raised  black  tubercles. 
Latreille  describes  these  organs  in  his  Nyct.  Blainvillii  as  possessing  a  somewhat  si- 
milar construction,  being  "  noir  et  compose  de  petits  grains  reunis  but  Mr.  Curtis 
characterizes  the  genus  with  "  eyes  and  ocelU  none?";  and  M.  Dufour,  in  his  descrip- 
tion of  the  species  which  he  names  Nyct.  Vespertilionis,  seems  to  consider  Latreille's 
account  erroneous,  stating  that  the  eye  in  that  species  is  "  d'un  blanc  grisatre,  tr^s- 
lisse  et  parfaitement  simple."  We  shall  subsequently  see,  from  the  description  of  my 
Chinese  species,  that  both  Latreille  and  M.  Dufour  are  correct. 
Fabricius,  Hermann,  and  Mr.  Curtis  characterize  the  genus  as  being  destitute  of 
antennoB ;  and  M.  Dufour  states  that  ' '  les  investigations  les  plus  scrupuleusement 
reiterees  ne  m'ont  pas  fait  decouvrir  le  moindre  vestige  d'antennes"  in  his  Nyct.  Vesper- 
tilionis. Latreille,  however,  describes  his  Nyct.  Blainvillii  as  being  furnished  with  two 
antenna,  inserted  in  the  superior  emargination  of  the  front  of  the  head,  very  short, 
contiguous,  advancing  parallelly,  and  two-jointed,  the  last  joint  being  the  largest,  and 
subtriangular,  but  rounded  externally.  M.  Dufour  therefore  considers,  without  much 
regard  to  the  weight  of  analogy,  that  these  organs  are  exclusive  to  Nyct.  Blainvillii.  In 
the  species  under  examination  they  exist  precisely  in  the  form  described  by  Latreille, 
which  I  need  not  repeat ;  as  well  as  in  all  the  individuals  of  other  species  which  I  have 
been  able  satisfactorily  to  examine.  As  these  organs  are  flat  and  closely  apphed  together 
at  the  interior  margin,  we  may  probably  not  be  far  from  correct  in  considering  that 
M.  Dufour  has  overlooked  them  as  distinct  organs,  regarding  them  as  the  produced 
front  of  the  head. 
The  structure  of  the  mouth  next  demands  our  attention.  The  description  of  it  given 
by  Fabricius  is  very  inaccurate,  since  he  describes  it  "  os  parum  prominens — vagina 
bivalvi — valvulis  obtusiusculis — palpi  triarticulati,"  &c.  With  the  exception  of  the  two 
large  external  organs,  which  they  have  considered  as  palpi,  Latreille  and  M.  Dufour 
w^ere  unable  to  ascertain  the  structure  of  the  oral  apparatus ;  and  the  figure  given  by 
Mr.  Curtis  of  the  head  does  not  convey  an  adequate  idea  of  its  organization. 
At  the  lateral  anterior  margins  of  the  head,  and  extending  beneath  a  short  distance 
into  its  inferior  emargination,  are  attached  a  pair  of  elongated  crustaceous  organs, 
strongly  setose,  which  are  advanced  in  front  of  the  head,  with  their  extremities  some- 
what dilated  and  brought  into  contact,  serving,  in  fact,  as  a  lateral  defence  of  the 
antenncB.  Their  interior  surface  is  smooth  ;  but  the  external  setcB  vary  considerably  in 
length,  some  of  them  being  as  long  as  the  organ  itself,  and  having  a  divergent  direction. 
As  to  the  nature  of  these  organs  I  may  observe,  that  having  discovered  the  existence  of 
distinct  antennas,  I  am  not  compelled  to  enter  with  M.  Dufour  into  those  philosophical 
speculations  as  to  the  gradual  degradation  and  transposition  of  the  functions  of  various 
organs  which  originated  in  the  supposed  want  of  antenna,  and  the  employment  of  the  sup- 
posed palpi  as  such.    By  Mr.  Curtis  they  are  doubtingly  considered  as  maxilla ;  which 
