This refers to Bentham's paper "On the Species and Genera of Plants, etc." "Nat.

Hist.

Review," April, 1861, page 133, which is founded on, or extracted from, a paper read before the Linn.
Soc., November 15th, 1858.

It had been originally set down to be read on July 1st, 1858, but gave way to the papers of Darwin and Wallace.
Mr.Bentham has described ("Life and Letters," II., page 294) how he reluctantly cancelled the parts urging "original fixity" of specific type, and the remainder seems not to have been published except in the above-quoted paper in the "Nat.

Hist.