114  SMITHSONIAN    MISCELLANEOUS    COLLECTIONS  VOL.    96 
than  I  cm  in  diameter,  is  visible  at  the  center,  surrounded  by  enamel, 
whereas  the  average  adult  walrus  tusk  has  a  dentin  layer  three  or 
four  times  this  size.  Most  of  the  harpoon  heads  were  apparently 
made  of  young  tusks  from  about  12  to  20  cm  long.  Further  evidence 
that  "  baby  "  walrus  tusks  were  used  in  this  way  is  shown  by  the  fact 
that  on  many  of  the  harpoon  heads  the  inner  side  of  the  basal  spur 
still  shows  the  original  hollow  of  the  proximal  end  of  the  tusk,  with 
an  inner  diameter  of  less  than  i  cm  as  compared  with  the  very  much 
larger  hollow  base  of  an  adult  tusk. 
With  regard  to  technique,  several  points  should  be  noted.  The  line 
holes  on  all  of  the  harpoon  heads  which  we  have  been  considering 
were  made  by  drilling  and  are  perfectly  round.  The  edges  were  usually 
trimmed  down  and  smoothed,  and  there  is  usually  a  rounded  depres- 
sion or  groove  extending  downward  from  the  line  hole ;  in  closed 
socket  heads  the  groove  is  usually  present  on  both  sides,  in  open  socket 
heads  only  on  the  back  side  at  the  place  where  the  lashing  slots  emerge. 
In  the  closed  socket  forms  the  socket  is  invariably  made  by  drill- 
ing and  consequently  is  cylindrical.  An  unexplained  feature  is  the 
occasional  presence  of  a  narrow  rectangular  slot  cut  through  to  the 
socket  from  one  or  both  sides  (pi.  23,  fig.  13;  pi.  26,  figs.  12,  19), 
possibly  for  the  purpose  of  facilitating  the  drilling. 
On  open  socket  heads  the  sockets  are  rectangular  and  were  made 
by  cutting.  In  the  older  examples  there  is  a  marked  tendency  for 
the  socket  to  be  relatively  shallow  with  a  somewhat  concave  bottom 
and  slightly  flaring  sides.  These  features  may  to  some  extent  be 
correlated  with  a  relatively  increased  size,  particularly  breadth,  but 
they  are  also  found  on  the  smaller  Old  Bering  Sea  heads,  such  as 
plate  24,  figures  2,  5-7,  11.  On  the  other  hand,  the  smaller  early 
Punuk  types  have  sockets  which  are  distinctly  narrower  and  deeper, 
with  flat  bottoms  and  vertical  sides. 
In  making  the  socket  one  of  the  first  steps  was  the  cutting  of  a 
small  transverse  slot  just  below  the  line  hole.  This  formed  the  upper 
end  of  the  socket  and  was  often  deeper  than  the  floor  of  the  socket. 
One  of  the  most  interesting  features  of  the  open  socket  heads  from 
a  technological  standpoint  is  the  lashing  arrangement — the  narrow 
rectangular  slots  on  either  side  of  the  socket  through  which  passed 
the  strands  of  baleen  or  sinew  which  held  the  end  of  the  foreshaft 
in  place.  On  the  older  heads  that  have  lateral  spurs  the  two  slots  are 
usually  of  unequal  length,  the  one  on  the  side  of  the  spur  averaging 
10  to  13  mm,  the  one  opposite  the  spur  8  to  10  mm;  on  the  later 
heads  the  slots  are  usually  of  equal  length,  averaging  around  10  mm. 
On  those  heads  which  have  median  spurs  the  lashing  slots  are  invari- 
