NO.    5      MALE  GENITALIA  OF  ORTHOPTEROID  INSECTS SNODGRASS         53 
The  structural  details  of  the  female  genital  region  are  well  known 
in  Blatta  and  Periplancta;  they  have  been  but  little  studied  in  forms 
in  which  the  male  organs  have  the  type  of  structure  exemplified  in 
Blattella  and  Ectohia,  though  Wille  (1920)  has  given  an  account  of 
the  female  genitalia  in  Blattella  gennanica  that  is  deficient  in  only 
one  essential  point. 
Most  of  the  external  genital  organs  of  the  female  of  Blattella 
germanica  are  exposed  by  depressing  the  seventh  abdominal  sternum. 
When  the  subgenital  sternum  is  carefully  cut  away  from  its  basal  con- 
nections, it  is  to  be  seen  that  the  lateral  and  anterior  walls  of  the 
cavity  above  it  (fig.  19  A)  are  formed  by  thick  membranous  folds 
(VIIIV)  converging  downward  and  forward  from  the  spiracular 
plates  of  the  eighth  tergum  {VIIIT).  The  folds,  therefore,  evidently 
represent  the  venter  of  the  eighth  segment,  and  the  several  asym- 
metrical sclerites  contained  in  them  (A,  C,  D,  h,  i,  j,  k),  as  well  as  a 
large  crescentic  sclerite  (A,  /)  in  the  roof  of  the  chamber  before  the 
ovipositor  (Ovp),  must  be  remnants  of  the  eighth  sternum.  Im- 
mediately behind  the  crescentic  dorsal  sclerite  (A,  /)  are  the  bases  of 
the  first,  or  ventral,  valvulae  of  the  ovipositor,  with  the  accompanying 
first  valvifers  (iVlf).  The  second  and  third  valvulae  arise  from  the 
venter  of  the  ninth  segment,  in  which  are  several  small  sclerites  linked 
with  the  ninth  tergum  by  a  pair  of  long  sclerotic  bars  (0,0)  extending 
forward  and  mesally  from  the  lateral  extremities  of  the  tergum.  The 
area  behind  the  ovipositor  includes  the  venter  of  the  tenth  segment 
and  the  under  surfaces  of  the  paraprocts  (Papf). 
The  mouth  of  the  median  oviduct  of  Blattella  (fig.  19  A,  Gpr)  is 
situated  on  the  end  of  a  soft  triangular  lobe  (in)  projecting  from  the 
anterior  wall  of  the  genital  chamber.  The  dorsal  surface  of  this 
genital  lobe  is  marked  by  a  deep  median  groove  (C,  D,  sg),  in  the 
anterior  end  of  which  are  the  apertures  of  the  two  spermathecae 
(D,  Spr,  Spr) .  Beneath  the  genital  lobe  is  a  flat  fold  of  the  integument 
(A,  C,  n)  that  contains  the  ventralmost  sclerite  {h)  referable  to  the 
eighth  sternum.  Another  sclerite  (D,  k)  lies  dorsally  on  the  left  side 
of  the  lobe,  and  two  sclerites  converge  above  it  (A,  i,  j)  from  the 
lateral  ventral  folds  of  the  eighth  segment.  The  general  conformation 
of  the  region  of  the  genital  opening  is  thus  quite  dififerent  in  Blattella 
from  that  in  Blatta  and  Periplaneta,  in  which  the  gonopore  is  on  the 
dorsal  surface  of  a  simple  fold  of  the  venter  of  the  eighth  abdominal 
segment,  and  the  spermathecal  aperture  is  located  on  a  small  sclerite 
in  the  dorsal  wall  of  the  genital  chamber  immediately  before  the  base  of 
the  ovipositor  (figs.  11  G,  15  G,  Spr).  The  two  spermathecal  aper- 
tures of  Blattella  are  far  in  advance  of  the  base  of  the  ovipositor,  and, 
