87 
them  were  able  to  bite.  When  one  penetrates 
deeper  into  the  woods,  found  on  the  banks 
of  all  the  rivers,  their  number  decreases  ra¬ 
pidly  while  that  of  C.  scapularis  increases. 
1.  Arribalzagae  is  found  exclusively  on  the 
banks  of  rivers  in  which  the  musty  breed,  as 
often  there  is  no  other  water  in  the  neigh¬ 
bourhood.  I  did  not  succeed  in  obtaining 
any  larvae  and  believe  that  they  either  live  in 
deep  water,  or  cling  to  plants.  At  the  waters 
edge  grew  a  continous  fringe  of  Eichhornia , 
but  their  immersed  parts  were  covered  with 
mud  and  we  found  no  larvae  on  them.  I  got 
many  eggs  of  /.  Arribalzage\  they  were  isola¬ 
ted,  black  and  like  those  of  Stegomyia  in 
shape.  Unfortunately,  though  1  made  repea¬ 
ted  and  prolonged  experiments  under  vary¬ 
ing  conditions,  no  larvae  were  hatched  ; 
this  points  to  very  peculiar  biologic  condi¬ 
tions.  The  period  of  incubation  is  probably 
very  long. 
Some  specimens  of  this  gnat  were  quite 
typical  but  others  seemed  to  form  a  transi¬ 
tion  to  /.  albigenu,  of  which  we  also  found 
characteristic  specimens.  /.  albigenu  is  pro¬ 
bably  only  a  vaiiety  ot  /.  Arribalzagae. 
The  other  two  species  of  lanthinosoma 
are  comparatively  rare,  evidently  because  they 
require  different  conditions. 
I  found  Mansonia  titillons  both  on  the 
upper  Paraná  (Tres  Lagoas,  Porto  Tibiriçá 
and  Mojoli  and  between  these  places)  and 
on  the  lower  part  of  the  river.  It  often 
came  on  board  at  dusk.  M.  titillans  is 
common  on  the  Salado  river  near  San 
Bernardino  (Paraguay).  In  the  earlier  part 
of  the  journey  we  saw  many  specimens  with 
reddish  scutum,  which  must  be  a  variety; 
typical  specimens,  with  brown  scutum,  ap¬ 
peared  further  South. 
On  the  Upper  Paraná,  I  found  two  spe¬ 
cimens  of  a  M.  species  I  had  already  seen 
on  the  San  Francisco  and  in  Pernambuco, 
where  I  found  its  larvae  onthe  roots  of 
Pistia  st  ratio  tes.  Perhaps  it  was  M. 
pseudotitillans ,  which  is  very  common  on  the 
Amazon.  On  this  journey,  we  only  saw  a  few 
specimens  of  P.  stratiotes  and  those  I  exami¬ 
ned  had  no  larvae  on  them.  Taeniorrhynchus 
species  were  conspicuously  rare  during  the 
whole  journey. 
Psorophora  ciliata  came  on  board  seve¬ 
ral  times,  both  in  the  Upper  and  on  the  Lo¬ 
wer  Paraná.  It  is  common  enough  in  Para¬ 
guay,  and  Dr.  MIGONE  collected  three  color 
varieties  of  it  near  the  river  Salado.  On  an 
excursion  to  this  river,  made  with  him,  we  also 
found  the  three  varieties.  Besides  the  typic 
form,  there  is  an  ochraceous  one  and  an  almost 
black  one,  which  must  not  be  mistaken  for 
Ps.  Holmbergi.  The  latter  is  restricted  to  a 
small  zone  ;  we  caught  only  one  female  that 
came  on  board  below  Paraná. 
In  the  Iguassu  falls,  I  noticed  some  Culex 
serratas  and  one  specimen  of  C.  crinifer. 
Wood  mosquitos  breeding  in  Bromeliae  were 
rare  because  there  were  few  of  these  plants, 
and  those  not  in  favorable  conditions;  at 
Iguassu  only,  did  1  obtain  some  larvae,  but 
they  were  not  very  interesting.  Some  of  the 
places  we  passed  were  covered  with  Chas¬ 
quea  gaudichaudi  and  would  be  very  suita¬ 
ble  for  studying  the  fauna  of  this  giant 
bamboo.  Unfortanately  they  had  flowered 
the  year  before  and  in  consequence  were 
dead.  Between  Porto  Mojoli  and  Porto  Mendes, 
we  found  a  few  living  ones,  from  which  I 
bred  Carrolia  iridescens  and  Hyloconops  Ion- 
gipalpis.  There  were  also  some  larvae  of 
Sabettinus  and  Megarrhinus  but  they  died 
on  the  journey. 
In  the  same  woods  grew  a  great  many 
specimens  of  Urera  subpeltata  MIQ  (?),  the 
stems  of  which  sometimes  hold  water.  Dr. 
ARAUJO  and  I  picked  and  examined  many 
of  them,  but  all  we  found  was  one  larva  of 
the  Dendromya  type.  We  did  not  succed  in 
raising  it,  so  the  species  remains  uncertain. 
We  intend  to  investigate  this  point  at  the 
earliest  opportunity. 
Chironomidae,  subfm.  Ceratopogoninae- 
Some  small  blood-sucking  Ceratopogom- 
nae  with  spotted  wings,  generally  known 
as  ltrnosquitos  polvora”,  or  “ polverinos ”  and 
belonging  to  the  genus  Culicoides,  were 
