Nearly two years were consumed in removing the matrix, piecing together and cementing the brittle and shattered petrified bone, strengthening it so that it would bear handling, and restoring the missing parts of the bones in tinted plaster.

The articulation and mounting of the skeleton and modelling of the missing bones took an even longer time, so that it was not until February, 1905, that the Brontosaurus was at last ready for exhibition.
[Illustration: Fig.

21 .-- Excavating the _Brontosaurus_ skeleton.
The upper photograph shows the anterior ribs of one side still lying in position.

The backbone is being prepared for removal, the sections each containing three vertebrae, partly cased in plaster and burlap (see chapter XI.) The lower photograph shows a later stage of progress, the blocks being undercut and nearly ready to turn over and incase the under side.

Strips of wood have been pasted into each section to strengthen it.] "It will appear, therefore, that the collection, preparation and mounting of this gigantic fossil has been a task of extraordinary difficulty.