The published images in Mark Catesby's Natural History are compared with the original watercolors now preserved in the Royal Library at Windsor Castle, England. This comparison has allowed for a more exact evaluation of the 174 plants illustrated by Catesby, resulting in determination of all plant species but one. The typification of most plant names is given in detail, with full bibliographic citations. Most non-plant organisms associated with the plant images are also identified and their nomenclatural status discussed. Catesby plates are newly designated here as lectotypes or neotypes for the following plant names: Cassine paragua Mill., Dracontium foetidum L., Echites umbellatus Jacq., Ficus citrifolia Mill., Fraxinus caroliniana Mill., Gleditsia aquatica Marshall, Hibiscus tiliaceus L., Ilex caroliniana Mill., Ipomoea catesbaei G.F.W. Mey., Laurus sassafras L., L. winterana L., Magnolia virginiana L. var. foetida L., Malva abutiloides L., Menispermum carolinum L., Passiflora cuprea L., Platanus occidentalis L., Quercus incana W. Bartram, Q. virginiana Mill., Rhizophora mangle L., Vanilla mexicana Mill., and Zanthoxylum clava-herculis L. As a result of this review, conservation proposals are being considered for two plant names (Quercus nigra L. and Plumeria alba L.) while rejection proposals are being prepared for one plant name (Smilax lanceolata to maintain S. smallii Morong). Two animal names (Eruca maximacornuta Edwards, an earlier name for Bombyx regalis Fabricius, the basionym of Citheronia regalis, the regal moth, and Papilio carolinianus Edwards, an earlier name for P. marcellus, the basionym of Protographium marcellus or Eurytides marcellus, the zebra swallowtail) are hereby suppressed as neither name has been accepted over the past one hundred years.