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MR.  T.  BELL  ON  THE  GENUS  CANCER. 
was  the  common  large  eatable  Crab  of  our  coasts,  the  Cancer  Pagurus,  Linn.  To  this  the 
name  Platycarcinus  was  given  by  Latreille ;  an  infehcitous  appellation  certainly,  as 
none  of  the  species  are  characterized  by  any  particular  degree  of  flatness  of  the  body, 
and  some  of  them  even  possess  a  rather  remarkable  degree  of  elevation.  Dr.  Edwards, 
with  great  correctness  and  tact,  united  to  the  genus,  thus  restricted  in  its  characters,  a 
second  species,  the  Cancer  irroratus  of  Say;  and  to  these  I  have  the  satisfaction  of  adding 
three  entirely  new  and  highly  interesting  species,  collected  by  Mr.  Cuming ;  an  acqui- 
sition which,  whilst  it  increases  our  opportunities  of  fixing  and  appreciating  the  cha- 
racters of  the  genus,  renders  a  complete  revision  of  it  necessary.  It  is,  indeed,  worthy 
of  remark,  that  the  specific  character  of  Cane.  Pagurus  as  given  by  Dr.  Leach  in  his 
'  Malacostraca  Podophthalma  Britannise,'  is  applicable,  with  very  little  latitude,  to  all 
the  species  now  known,  as  they  agree,  without  exception,  in  the  margin,  on  each  side, 
having  nine,  or  more  properly  ten  divisions  (the  last  being  obsolete),  in  the  front  being 
trifid,  and  the  carapax  granulated. 
The  application  of  the  name  Cancer  to  the  present  genus  renders  it  necessary  to  attach 
a  new  generic  term  to  the  group  to  which  Dr.  Edwards  had  appropriated  it,  and  which 
he  has  characterized  with  his  accustomed  discrimination.  It  is  very  nearly  allied  to 
Carpilius,  from  which  some  of  the  species  scarcely  differ  except  in  the  form  of  the  legs, 
which  in  Carpilius  are  round,  and  in  the  other  group  much  flattened  and  fringed  with 
hair.  I  propose  for  this  genus  the  name  Platypodia ;  and  I  conceive  that  in  making 
these  alterations  in  the  nomenclature  of  this  family,  I  am  not  intrenching  on  any  of  the 
acknowledged  rules  by  which  these  matters  are  generally  regulated,  but  rather,  by  so 
early  an  interference,  contributing  to  their  establishment. 
The  genus  Platypodia  on  the  one  hand  approximates  to  Carpilius  by  Plat,  rosea  and 
Plat,  interrupta,  and  on  the  other  to  Zozymus  by  Plat,  lobata. 
Genus  Cancer,  Leach.    (Platycarcinus,  Latr.,  Edw.) 
Antenna  externcB  articulo  basilari  maximo,  antic^  in  dentem  fortem  producto,  hiatum 
inter  frontem  et  canthum  internum  oculi  implente  :  portione  mobili  setacea,  brevi, 
propius  foveolse  antennae  internse  quam  cantho  interno  oculi  inserta. 
AntenncB  internee  foveolis  longitadinalibus,  antrorsum  porrectse. 
Pedipalpi  externi  caulis  interni  articulo  secundo  ad  marginem  antico-internum  excavato. 
Pedum  par  anticum  subinaequale,  paria  reliqua  ambulatoria. 
Abdomen  maris  5-  foeminse  7-articulatum. 
Oculi  pedunculo  brevi. 
Testa  transversa,  lata,  elliptic^  arcuata,  marginibus  antico-lateralibus  decem-lobatis, 
lobo  posteriore  obsoleto  ;  fronte  trifido. 
The  shell  in  this  genus  is  broad,  elliptical,  somewhat  elevated,  and  with  the  regions 
rather  distinctly  marked.  The  surface  in  all  the  species  hitherto  known  is  more  or 
less  granulated.    The  front  is  trifid,  the  middle  tooth  being  sometimes  lost  in  very  old 
