NO.    5      MALE  GENITALIA  OF  ORTHOPTEROID  INSECTS — SNODGRASS        47 
it  is  the  same  cavity  within  a  large  capsular  sclerite  (in).  This  inter- 
phallic  cavity  of  the  Blattinae,  with  its  strongly  developed  walls  and 
closing  valve,  must  have  some  important  function  connected  with  the 
insemination  of  the  female.  According  to  Zabinski  (1933  a)  Blatta 
orientalis  produces  a  spermatophore  (fig.  iiH),  though  nothing  is 
known  of  the  place  or  manner  of  its  formation.  Structural  details  of 
the  phallic  organs  in  several  species  of  Periplaneta  are  shown  by 
Walker  (1922),  and  Crampton  (1925)  gives  a  complete  nomen- 
clature for  all  the  phallic  parts  of  P.  americana.  The  right  and  left 
phallic  lobes  are  the  "  parameres  "  of  Walker,  who  calls  the  ventral 
lobe  the  "  penis."  Crampton,  however,  designates  as  the  "  penis  " 
a  small  lobe  on  the  base  of  the  ventral  phallomere,  which  is  evidently 
a  part  of  the  interphallic  fold  containing  the  phallotreme.  Eurycotis, 
as  described  and  figured  by  Chopard  (1920),  would  appear  to  have 
the  same  type  of  phallic  structure  as  Blatta  and  Periplaneta,  and  the 
same  is  true  of  Blaherus  atropos  described  by  Walker,  though  the 
phallomeres  of  this  species  are  not  of  the  t3'pical  blattine  form. 
The  immature  phallomeres  of  Periplaneta  americana  consist  of 
three  small  lobes  similar  to  those  of  Blatta.  In  a  nymph  31  millimeters 
long  (fig.  15  A)  the  left  phallomere  is  already  partly  subdivided  into 
accessory  lobes  (B).  If  a  specimen  of  this  instar  is  in  a  premoulting 
condition,  the  phallomeres  of  the  next  instar  (C),  contained  within 
the  loosened  cuticula,  will  be  found  to  have  a  shape  more  suggestive 
of  that  of  the  adult  organs. 
The  second  type  of  blattid  phallic  structure,  which  is  well  exem- 
plified in  Blattella  gcrmanica,  is  characterized  by  the  absence  of  the 
ventral  phallomere,  by  a  simplification  of  the  other  two  phallomeres, 
which  are  mostly  invaginated  into  right  and  left  pouches  of  the  genital 
chamber  w^all,  and  by  the  development  of  an  eversible  median  lobe 
containing  the  opening  of  the  genital  exit  passage.  The  median  lobe 
appears  to  be  a  secondary  evagination  at  the  mouth  of  an  eversible 
endophallic  sac ;  when  protracted  it  forms  an  intromittent  organ,  and 
may  therefore  be  teniied  the  penis,  in  a  functional  sense. 
In  Blattella  germanica  the  external  genital  organs  and  the  proctiger 
are  concealed  between  the  long  tenth  tergum  and  the  shorter,  asym- 
metrical ninth  sternum  (fig.  17  A).  The  proctiger  is  a  membranous 
cone  (C,  Ptgr)  arising  beneath  the  base  of  the  tenth  tergum ;  it  bears 
the  anus  at  its  apex  and  a  pair  of  lateral  hooks  (a,  h)  on  its  base,  but 
it  shows  no  differentiation  into  epiproct  and  paraprocts.  The  sub- 
genital  sternum  (A,  IXS)  bears  two  small  styli  {Sty)  on  its  distal 
margin,  and  has  a  pair  of  long  apodemes  (IXSAp)  projecting  into  the 
body  cavity  from  its  concealed  anterior  margin.  On  the  left  side  of  its 
