56  SMITHSONIAN    MISCELLANEOUS    COLLECTIONS  VOL.    96 
depressions  of  the  integument  at  the  bases  of  the  seventh  and  eighth 
tergal  plates  (see  Oettinger,  1906;  Wille,  1920).  Into  each  of  these 
depressions  opens  a  pair  of  glands,  the  first  between  segments  VI  and 
VII,  the  second  between  segments  VII  and  VIII.  The  glands  of 
Blattella,  according  to  Oettinger  and  Koncek,  are  similar  to  those  of 
Periplaneta,  though  located  on  different  segments,  but  they  are  present 
only  in  adult  males.  The  secretion  of  the  male  glands  in  Blattella,  as 
suggested  by  Sikora  (1918)  and  demonstrated  by  Wille  (1920),  is 
attractive  to  the  females  at  the  time  of  mating  and  induces  the  female 
to  mount  the  back  of  the  male  preliminary  to  copulation.  The  glands 
thus  have  a  function  similar  to  that  of  the  back  glands  of  certain  male 
crickets. 
Wille  (1920)  describes  the  mating  and  copulation  of  Blattella 
germanica  as  follows:  When  a  male  encounters  a  prospective  mate 
he  takes  a  position  either  face  to  face  with  her  or  at  her  side.  After 
a  short  interplay  of  the  antennae,  the  male  raises  his  wings  at  right 
angles  to  his  body,  turns  himself  about,  and  brings  the  end  of  his 
abdomen  close  to  the  head  of  the  female.  The  depressions  on  the  back 
of  the  male  are  thus  exposed  to  the  female,  who,  being  soon  attracted 
to  them,  first  explores  them  with  her  palpi  and  then  proceeds  to  lick 
them  with  her  mouth  parts.  When  the  female  becomes  absorbed  in 
this  occupation,  the  male  suddenly  makes  a  backward  movement, 
thrusting  his  abdomen  under  that  of  the  female,  until  the  female's 
head  is  almost  against  the  bases  of  his  upstanding  wings.  From  the 
abdomen  of  the  male,  already  extended  at  its  tip,  there  is  now 
projected  the  long,  hooked  left  phallomere  ("  titillator ")  and  the 
penis.  The  first  grasps  and  pulls  down  the  subgenital  plate  of  the 
female,  while  the  second  is  turned  upward  and  forward  and  thrust  into 
the  female's  genital  chamber.  In  the  following  discussion  of  the  act 
of  insemination,  Wille  appears  to  assume  that  the  spermatozoa  are 
discharged  into  the  oviduct ;  he  describes  the  means  by  which  the  penis 
might  be  guided  toward  the  "  vaginal  "  orifice  in  such  a  manner  that 
the  genital  openings  of  the  two  sexes  would  be  pressed  together ;  he 
makes  only  an  incidental  mention  of  a  sperm  receptacle,  and  does  not 
observe  the  separate  spermathecal  openings  in  the  spermatic  groove 
above  the  gonopore.  It  would  seem  more  probable,  therefore,  that 
the  virga  of  the  penis  is  laid  in  the  seminal  groove  of  the  female  genital 
lobe,  and  that  the  spermatozoa  are  thus  guided  from  the  exit  orifice  of 
the  penis  to  the  spermathecal  apertures. 
Zabinski  (1933),  who  studied  the  mating  habits  of  several  common 
species  of  roaches,  claims  that  the  male,  after  having  secured  a  hold 
on  the  genitalia  of  the  female,  turns  end  to  end  from  her,  and  that 
