MANTELL, Gideon Algernon. The Fossils of the South Downs; or Illustrations of the Geology of Sussex. London: Lupton Relfe, 1822. First edition. Half-title, 4pp. 'Subscribers', 42 aquatint plates engraved by Mrs. Mantell, including 4 hand-coloured and 2 folding, 1p. publisher's advertisement to rear. (Spotting to frontispiece, browning, marginal spotting to plates, some corner creases, toning.) [Bound with:] MANTELL, Gideon Algernon. Illustrations of the Geology of Sussex: Containing a General View of the Geological Relations of the South-Eastern Part of England; with Figures and Descriptions of the Fossils of Tilgate Forest. London: Lupton Relfe, 1827. First edition. 3pp. 'Subscribers', 1 folding colour lithographed sectional plan, 21 lithographed plates, including 2 folding. (Browning, mild to moderate spotting to plates, some offsetting.) 4to (293 x 201mm.) Near contemporary brown half calf over marbled paper-covered boards, two red morocco lettering pieces to the spine (surface loss to covers, rubbing to lower lettering piece). Note: Mantell's first two works- and considered the most important. Provenance: Richard Shuttleworth (armorial bookplate to the front pastedown); by descent, from the estate of Rendel Williams.