68  SMITHSONIAN    MISCELLANEOUS    COLLECTIONS  VOL.    96 
distal  angles  of  the  sternal  process.  The  concave  dorsal  wall  of  the 
ninth  sternum  becomes  proximally  a  deep  concavity  in  which  the 
phallus  (Phi)  is  lodged.  The  tenth  tergum  (A,  B,  XT)  is  a  large 
triangular  plate  with  its  apex  produced  into  a  thick  median  stalk 
bearing  two  strong  terminal  lobes  that  embrace  the  process  of  the 
ninth  sternum  when  the  tenth  tergum  is  depressed.  The  venter  of  the 
tenth  segment  is  a  narrow  membranous  area  proximal  to  the  para- 
procts  (C,  X.V).  The  eleventh  segment  projects  ventrally  from 
beneath  the  broad  basal  part  of  the  tenth  segment  (A,  C)  ;  the  epiproct 
is  produced  into  a  prominent,  laterally  compressed  lobe  (Eppt)  ;  the 
paraprocts  (Papt)  are  two  small,  soft  lobes  at  the  base  of  the  epiproct. 
The  anus  (C,  An)  lies  in  the  anterior  end  of  a  deep  depression  on  the 
under  surface  of  the  epiproct.  The  falciform  cerci  (A,  B,  C,  Cer) 
are  articulated  by  their  basal  sclerites  to  the  proximal  parts  of  the 
lateral  margins  of  the  tenth  tergum  (A). 
The  phallus  of  Phaneroptera  furcata  is  a  thick,  padlike  organ  arising 
from  the  anterior  wall  of  the  genital  chamber.  In  its  usual  condition  it 
is  contained  in  the  dorsal  concavity  on  the  base  of  the  ninth  sternum 
(fig.  25  A,  Phi),  where  it  is  concealed  by  the  overhanging  lobe  of  the 
epiproct.  The  broad,  sloping  posterior  surface  of  the  phallus  (D,  E) 
presents  a  median  depression  dorsally  between  prominent  marginal 
folds  (/)  that  terminate  distally  in  the  lateral  phallic  lobes  {II).  The 
ventral  lobe  is  a  tonguelike  extension  of  the  ventral  lip  of  the  broad 
phallotreme  (E,  vl),  which  may  be  folded  back  into  the  latter  (D). 
The  floor  of  the  dorsal  cavity  is  roundly  convex  and  is  crossed  by 
foul",  narrow,  dark-lipped  grooves.  Distally,  it  bears  a  pair  of  promi- 
nent oval  swellings  {h),  conspicuous  by  their  darker  color,  which 
results  from  a  dense  covering  of  small  spines  such  as  are  more  sparsely 
distributed  on  the  surrounding  surface.  The  interior  of  the  dorsal 
lobe  of  the  phallus  is  occupied  by  two  dense  masses  of  muscle  (F,  mcl) 
the  fibers  of  which  arise  laterally  within  the  phallus  and  curve  medially 
and  dorsally  to  their  insertions  on  the  arched  floor  of  the  dorsal  cavity. 
In  the  retracted  condition  the  base  of  the  phallus  is  covered  dorsally 
by  a  transverse  fold  of  the  genital  chamber  wall  (D,  E,  F,  ;'). 
The  apparently  abrupt  change  in  the  structure  of  the  phallus  from 
the  simple  nymphal  condition  to  the  complex  adult  form,  as  illustrated 
in  Conocephaliis  fasciatus  (fig.  23  G,  H),  is  of  course  more  gradual 
than  it  appears.  The  adult  modifications  take  place  during  the  last 
nymphal  instar  within  the  cuticula  of  the  nymphal  phallus,  and  are 
completed  at  ecdysis.  The  mature  phallus  of  C.  fasciatus  (fig.  23  H) 
much  resembles  that  of  C.  hrevipennis  described  and  figured  by 
Walker  (1922).    In  the  retracted  condition  the  phallus  projects  but 
