su 
Of  very  large  size  (over  130  mm.),  slate  grey  in  colour, 
with  two  conspicuous  white  spots  upon  the  upper  side  of 
the  anterior  half  of  segments ,  side  margins  of  the  keels  tri- 
dentate  or  quadridentate ,  the  pores  widely  separated  from 
this  edge;  sterna  with  two  pairs  of  spinules.  .  .  mirandus. 
Of  medium  size  (less  than  100  mm.),  chocolate  brown  in 
colour,  keels  often  flavous,  with  their  margins  less  strongly 
dentate  and  the  pores  closer  to  them. 
a5.  The  distance  between  the  pores  and  the  lateral  margin 
greater  than  the  diameter  of  the  rim  of  the  pore. 
a6.  Collum  scarcely  carinate  and  only  a  little  wider  than 
the  head  ;  tail  with  strongly  convex  border  ;  granula- 
tion finer,  margins  of  keels  scarcely  lobulate  
xanthopus. 
bQ.  Collum  distinctly  carinate ,  considerably  wider  than  the 
head  ;  tail  more  squared  ;  granulation  coarser,  edges  of 
the  keels  more  clearly  lobulate  laticollis. 
¥.  The  distance  between  the  pores  and  the  edge  less  than 
the  diameter  of  the  porous  area. 
a7.  The  sternal  areas  armed  with  two  pairs  of  spines, 
one  spine  at  the  base  of  each  leg,  tail  oval. 
a8.  Keels  narrower  at  the  base,  not  shouldered,  those 
at  the  posterior  end  of  the  body  produced  behind 
into  a  long  slender  spiniform  process;  sternal  spines 
small,  tuberculiform ;  granulation  of  terga  finer.  . 
monticola. 
5s.  Keels  broad  at  the  base,  shouldered,  those  at  the 
posterior  end  much  less  acutely  spiniform;  sternal 
spines  longer  ;  granulation  of  terga  coarser  
subspinosus. 
b1.  Sternal  areas  unarmed,  keels  distinctly  shouldered. 
a9.  Posterior  keels  with  their  posterior  angles  pro- 
duced into  a  long  spiniform  process. 
a10.  Tail  subquadrate,  with  long  parallel  sides  and 
lightly  convex  posterior  border;  granulation 
coarse  humberti. 
Tail  parabolic,  with  widely  rounded  posterior 
border  ;  granulation  much  finer  .  .  flavisternus. 
