This  species  is  said  by  Saussure  and  Humbert  to  be  very  like  S.  nietanus,  which
also  came  from  Cuernavaca,  but  to  differ  in  having  the  lateral  portions  of  the  first
tergal  plate  much  less  narrowed  and  emarginate  and  provided  with  longitudinal  sulci
near  its  posterior  margin  and  also  in  having  the  inferior  sulci  much  stronger  and
extending  up  to  the  pores.  It  may  also  be  added  that  the  tergal  plates  are  thickly
punctured  dorsally,  whereas  in  S.  nietanus  they  are  described  as  smooth.
86  DIPLOPODA.
4.  Cyclothyrophorus  vulvanus.
Spirobolvs  vulvanus,  Karscli,  Zeitschr.  ges.  Naturwiss.  (3)  vi.  (liv.)  p.  55  (1881).
Colour  black,  with  the  posterior  borders  of  the  tergal  plates  flavous.
Head  nearlj'  smooth,  with  3  or  4  labral  pores  on  each  side ;  area  between  the  antennae  impressed.  First  tergal
jAate  with  its  lateral  portion  extending  interiorly  as  far  as  that  of  the  second,  narrowed,  subacute,  the
anterior  margin  excavated  and  defined  by  a  sulcus.  The  rest  of  the  segments  with  the  transverse  sulcus
not  deep  ;  the  median  portion  very  finely  subrngose,  sculptured  with  longitudinal  stria;  and  scattered
punctures  ;  inferiorly  striate,  posterior  portion  slightly  convex,  sulcate  beneath,  sparsely  impressed  with
punctures,  marked  with  a  median  dorsal  sulcus  and  a  lateral  sulcus  behind  the  pore,  which  is  placed
behind  the  transverse  sulcus.  Anal  segment  punctured  ;  tergal  plate  widely  rounded ;  valves  strongly
convex,  vulviform.
Number  of  segments  43.     Length  30  millim.
Hab.  Mexico,  Puebla  {BercJcenhusch).
