50 
SMITHSONIAN    MISCELLANEOUS    COLLECTIONS  VOL.    96 
the  rudiment  of  the  virga,  and  evidently  cannot  represent  the  median 
ventral  phallomere  of  Blatta  or  Periplaneta  because  of  its  position 
dorsal  to  the  genital  opening. 
The  external  genitalia  of  Ectobius  lapponicus  have  the  same  type 
of  structure  as  those  of  Blattella,  but  in  most  respects  they  are  simpler. 
The  exposed  part  of  the  ninth  abdominal  sternum  of  the  adult  male 
Fig.  17. — Blattoidea:  abdomen  and  external  male  genitalia  of  Blattella  ger- 
manica  (Linnaeus). 
A,  adult  male,  end  of  abdomen,  ventral  view.  B,  same,  vi^ith  left  phallomere 
projected.  C,  same,  proctiger  and  basal  hooks  (a,  b)  beneath  tenth  tergum, 
ventral  view.  D,  nymph  3  mm  long,  abdomen,  ventral  surface.  E,  nymph  22  mm 
long,  end  of  abdomen,  ventral  view.  F,  same,  phallic  lobes  removed  from  geni- 
tal chamber,  dorsal  view.  G,  left  phallomere  of  following  nymphal  instar  taken 
from  within  cuticula  of  left  lobe  of  F.   H,  left  phallomere  of  adult. 
For  letter  explanation,  see  preceding  figures. 
forms  an  asymmetrically  triangular  subgenital  plate  (fig.  i8  A,  B, 
IXS)  projecting  far  beyond  the  short  tergum  of  the  tenth  segment 
(A,  XT),  and  bearing  the  coalesced  rudiments  of  the  styli  (B,  Sty) 
at  its  apex.  The  anterior  invaginated  part  of  the  ninth  sternum  (E) 
is  produced  into  two  long  apodemal  arms  (IXSAps)  extending  far 
forward  in  the  abdomen,  the  left  arm  being  longer  than  the  right. 
Above  the  external  part  of  the  ninth  sternum  is  the  genital  chamber, 
