121 
Legs  strong,  short  and  thick.  Tarsi  broad 
and  flat.  Ungues  slighly  bent,  pulvilli  rec¬ 
tangular  and  broad,  shorter  than  the  ungues. 
Abdomen  thick,  heart-shaped,  inclining 
to  globolar  form.  Last  ring  semilunar,  with 
an  arched  postero-inferior  incision  in  the  male 
which  embraces  the  broad  flat,  shield-like 
genital  ring;  in  the  female,  it  has  an  angu¬ 
lar  inferior  border,  orming  a  triangular  or 
quadrangular  fissure  enclosing  the  small  se¬ 
milunar  genital  segment. 
Larvae :  Ovoid,  thick,  with  a  pair  of 
oral  hooks  on  the  cephalic  segment. 
Antennae  nipple-shaped  with  two  chiti- 
nous  rings,  recalling  ocelli;  anterior  stigma 
forming  transversal  slits  between  the  cepha¬ 
lic  ring  and  the  next  one.  Body  convex 
above,  concave  below,  with  longitudinal  fur-  j 
rows.  On  segments  3  —  9  three  pairs  of  late¬ 
ral  elevations  bearing  strong  thorns  or  sharp 
prickles  (BRAUERJ,  or  covered  with  smooth 
scales  (AUSTEN).  The  last  ring  of  the  body 
is  glabrous  and  may  be  retracted  into  the 
preceeding  one  thus  forming  a  stigmatic  cavi¬ 
ty:  it  is  narrower  and  shorter  than  the  pre¬ 
ceeding  rings.  Posterior  stigmata  crescent  or 
kidney  shaped.” 
The  callosities  of  the  face  and  some 
smaller  ones  on  the  pleura  and  the  abdomen 
characterise  the  genus,  but  are  of  little 
use  in  distinguishing  the  species,  as  their  ar¬ 
rangement  is  the  same  in  all  of  them.  They 
may  vary  in  size,  but  also  in  individuals  of 
the  same  species,  as  the  tomentum  around 
them  is  easily  rubbed  off.  Size  and  shape  of 
the  antennae  vary  somewhat  in  the  different 
species  and  may  be  used  for  classification. 
The  pattern  of  the  skin  of  known  arvae 
and  pupae  may  be  used  for  recognising  them 
as  it  seems  different  in  the  three  species  in 
my  collection. 
Their  host  may  also  furnish  important 
data  as,  unlike  Dermatobia ,  all  the  known 
species  are  very  specialised  in  their  choice 
of  them. 
Alulae  and  squamulae  are  large,  striking 
and  very  characteristic  ;  so  are  the  delicate 
folds  on  the  wings,  though  they  may  be 
found  in  some  other  flies. 
Cuterebra  apicalis  has  a  red  band  across 
its  dark  eyes,  a  fact  I  first  noticed  in  a  live 
female.  When  the  insect  dies,  the  band  disap¬ 
pears  rapidly  and  was  therefore  not  known. 
I  shall  now  describe  the  species  observed; 
no  key  is  needed,  as  those  described  by  me, 
can  be  recognised  by  the  illustrations  ;  the 
other  descriptions  cannot  very  well  be  used, 
unless  they  are  compared  with  the  types. 
1.  Cuterebra  apicalis  GUÉRIN 
(PI.  27,  fig.  1  ;  PI.  29,  tig  1  face  of  2  ;  fig.  la  face  of  J .) 
This  is  the  most  common  species  and 
is  found  more  often  than  all  the  others  to¬ 
gether.  It  may  be  readily  recognised  by  the 
illustration,  but  to  avoid  confusion  with  other 
doubtful  or  similar  species,  I  add  a  few 
words.  It  is  medium-sized  ;  the  body  of  the 
largest  specimen,  a  male,  is  23  mm.,  the  wing 
16  mm.  long;  while  the  smallest  measures  are 
17  mm.  for  the  body  and  14  for  the  wing,  the 
length  of  the  body  varying  more  than  that  of 
the  wing.  The  ground  color  of  both  body 
and  wing  is  chestnut  or  rusty  brown. 
On  the  dorsum  of  the  abdomen,  it  becomes 
!  nearly  black  but  keeps  its  steely  blue  glint  ; 
on  the  legs  it  may  be  dark  reddish  brown, 
i  but  never  black,  though  the  hairs  on  them  are 
¡  black  ;  the  frontal  calli  are  piceous.  The  to¬ 
mentum  on  the  scutum  (which  in  well  pre¬ 
served  specimens  is  thick  and  velvety)  is  ge¬ 
nerally  ochraceous  and  sometimes  becomes 
j  whitish  or  reddish-yellow;  it  varies  a  little, 
according  to  the  way  in  which  the  light 
strikes  it,  as  the  ground  colour  is  perceived 
when  the  tomentum  is  rather  thin.  In 
I  a  specimen  from  JOINVILLE,  the  ground  is 
so  exceptionally  daik  that  the  scutum  looks 
blackish  and  the  scutellum  (the  ground  of  which 
ought  to  be  hidden  by  the  tomentum,  in  well- 
preserved  specimens)  looks  almost  black. 
(Perhaps  cayennensis  is  only  a  dark  specimen 
of  apicalis  which  is  very  likely  to  be  found 
in  Cayenne  ;  whether  ephippium  LATR.  is 
synonymous  seems  more  doubtful).  The  wings 
have  a  rather  weak  blackish  yellow  ground 
color  which  is  darker  in  the  female  than  in 
the  male;  the  alulae  of  both  sexes  are  con¬ 
siderably  darker  than  the  wings.  The  eyes 
