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process  in  the  same  straight  line  as  the  tergite,  its  sides  slightly 
converging;  its  apex  truncate  and  bifid.  Anal  sternite  with  convex 
border,  the  tubercles  small.  Sterna  normal,  unspined.  Legs  of  moderate 
length. 
Length  about  30  mm.;  width  3.5. 
This  species  differs  from  the  preceding  in  colouring,  in  being  more 
convex;  in  the  different  form  of  its  keels,  the  absence  of  the  inferior 
crest,  the  straightness  of  the  caudal  process  etc. 
Centrodesmus ,  gen.  nov. 
Antennœ  very  long  and  slender,  separated  by  a  space  equalling  the 
length  of  the  basal  segment ,  which  is  short  being  about  *  the  length 
of  the  rest;  the  2»*  to  the  6*  subcylindrical ,  and  subequal  in  length. 
The  first  tergite  with  very  large,  basally  expanded,  distally  pointed 
keels. 
The  rest  of  the  segments  strongly  keeled.  The  keels  situated  on 
the  summit  of  the  sides,  directed  upwards  and  backwards  and  inclined 
to  the  plane  of  the  dorsal  surface  at  an  angle  of  from  45°  to  50°; 
keels  slender,  subcylindrical,  crescentic;  much  narrower  at  the  base 
than  the  keel-bearing  part  of  the  segment;  the  keels  of  the  19^  seg- 
ment tuberculiform. 
Pores  conspicuous,  just  beneath  the  margin  of  the  keels,  situated 
about  -J-  of  the  distance  from  the  apex,  on  the  following  segments 
<•  e.  5,  7,  9,  10,  12,  13,  15,  16,  17,  (18)  ^  but  not  visible  on 
the  tuberculiform  keels  of  the  19th. 
Anal  tergite  triangular,  wide  at  the  base,  very  slender  in  front  of 
the  apex  which  is  truncate,  with  two  pairs  of  tubercles  on  the  upper 
surface  towards  the  apex  and  two  dentiform  tubercles  on  each  side 
along  the  lateral  margin. 
Anal  sternite  triangular,  with  the  apex  pointed,  bitubercular. 
Legs  very  long  and  slender. 
1)  The  keels  of  this  segment  are  fractured  distally,  so  I  can  not  positively  assert 
that  they  possessed  pores.  But  since  these  keels  are  of  large  size  and  similar  to  those 
of  the  17th  segment,  there  are  no  reasons  for  supposing  them  to  be  devoid  of  pores. 
