I would bet you that the surface Grace Eager used was Ross Board, 00
or coarser.  It is almost impossible to see the texture on 00 by eye,
but a scanning electron microscope picture of the surface is in the
Guild Handbook, chapter 3, I think.  You can see the texture on the
coarser versions, No.1, 1 1/2, 2, 8, and they look like coquille
board.  However, Ross Board was clay (or calcium) coated, like
scratchboard (in fact Mr. Ross made a smooth scratchboard for
inking).  Actually, Ross Board is textured "scratchboard."  Ess Dee
in England made textured scratchboard for a while but has
discontinued it.  Ross Board died in the 1960's when Mrs. Ross walked
away from her house and the production of the board some years after
Mr. Ross and later his helpers died.  Wes Gardner tried to obtain the
recipe for the coating but Mrs. Ross refused to sell it to him.  Wes's
story about all this history is in an old issue of the GNSI
Newsletter.
   Grace Eager was a teacher of Elsie Froeschner, my predecessor in
the entomology illustration job at Smithsonian, when Elsie worked at
Univ. of Michigan.  Elsie retired over 20 years ago, and I "retired"
last year.  Don't know when Grace died, but Elsie is about 83.  Bill
Brudon and Gerry Hodge in Ann Arbor may know more history and can
identify that surface for you.
  Elaine