Labelled 'General Index' which follows on from the first General Index reference Coll-203/A5/1, both of which link back to indexes referenced Coll-203/A5/2-11. Undated, the works included date from 1837 until 1874. This index has each page split into 5 columns. the first column lists authors alphabetically, followed by the titles of their work (article or book) and date, followed by a note of the relevant index notebook - and tract (series of bound Offprints). These two General Indexes (Coll-203/A5/1 and Coll-203/A5/12 are therefore the key to the authors and works that Lyell is reading and where that reading to bound into the bound Offprints.