The  case  is  very  different  with  the  males  of  many  other
animals.  We  see  this  in  the  horns  of  stags  and  of  certain
kinds  of  antelopes  in  which  the  females  are  hornless.  With
many  animals  the  canine  teeth  in  the  upper  or  lower  jaw,
or  in  both,  are  much  larger  in  the  males  than  in  the
females,  or  are  absent  in  the  latter,  with  the  exception
sometimes  of  a  hidden  rudiment.  Certain  antelopes,  the
musk-deer,  camel,  horse,  boar,  various  apes,  seals,  and  the
walrus,  offer  instances.  In  the  females  of  the  walrus  the
tusks  are  sometimes  quite  absent.*  In  the  male  elephant
of  India  and  in  the  male  dugoug  \  the  upper  incisors  form
offensive  weapons.  In  the  male  narwhal  the  left  canine
alone  is  developed  into  the  well-known,  spirally-twisted,  so-
called  horn,  which  is  sometimes  from  nine  to  ten  feet  in
length.  It  is  believed  that  the  males  use  these  horns  for
fighting  together;  for  *^an  unbroken  one  can  rarely  be  got,
and  occasionally  one  may  be  found  with  the  point  of
another  jammed  into  the  broken  place."!  ^^^^  tooth  on
the  opposite  side  of  the  head  in  the  male  consists  of  a  rudi-
ment about  ten  inches  in  length,  which  is  embedded  in  the
jaw;  but  sometimes,  though  rarely,  both  are  equally  devel-
oped on  the  two  sides.  In  the  female  both  are  always  rudi-
mentary.    The  male  cachalot  has  a  larger  head  than  that

*  Mr.  Laraont  ("Seasons  with  the  Sea-Horses,"  1861,  p.  143)  says
that  a  good  tusk  of  the  male  walrus  weighs  four  pounds,  and  is
longer  than  that  of  the  female,  which  weighs  about  three  pounds.
The  males  are  described  as  fighting  ferociously.  On  the  occasional
absence  of  the  tusks  in  the  female,  see  Mr.  R.  Brown,  "  Proc.  Zool.
