  Lyell pretty clearly assumes that to allow for evolution is to deny the reality of species. For a species to be ‘real’, it must have ‘permanent existence in nature’, or as he puts it elsewhere , “…fixed limits beyond which the descendants from common parents can never deviate from a certain type…”. (Lyell 1831, II. 23) To accept evolutionary change, on this view, you must become comfortable with a variety of nominalism about species. And Darwin seems to have become  so.[9] 