One of the great scientists of colonial Mexico, Martin de Sessé y Lacasta arrived in Mexico City from his native Aragon in 1780. A founder of the Botanical Garden in Mexico City, Sessé was also co-leader of the sixteen year long Royal Botanical Expedition, which surveyed the flora and fauna of the Spanish colonies from California to Costa Rica. Sessé returned to Spain in 1803 to write up the results of his expedition, but died before completing the project. The results were finally published in 1887, when they appeared as Plantae Novae Hispaniae and Flora Mexicana. The Catalogo de animales y plantas Mexicanas by Martin de Sessé y Lacasta represents a catalog of plant and animal specimens collected by the Royal Botanical Expedition in Mexico as of 1794. The manuscript is arranged in three parts: a brief letter of introduction to the Conde Revillagigedo (11p.), an inventory of animal specimens (52p.), and an inventory of the plants (163p.). The plant and animal sections are organized by Linnaean class, with a code indicating whether they were drawn from life, whether a specimen was collected, and whether the species was new to science.