Introduction. — By far the most important and fundamental carcinological publication of the first half of the 19th century unquestionably is Henri Milne Edwards's (1834-1840) "Histoire naturelle des Crustacés", which treated all species of Crustacea known at that time in an exceedingly clear and comprehensive manner. The work was published in three volumes of text and one atlas. The dates of publication of it have never caused any difficulty. It was generally accepted that volume I was published in 1834, volume II in 1837, and volume III in 1840. These dates have never been challenged, and on closer examination indeed prove to be correct. About the date or dates of the atlas authors were vague and usually cited 1834-1840, or 1840, or they cited the atlas without any date. As the illustrations are accompanied on the plates with their French vernacular generic names only, the exact dates of the plates were of no nomenclatural interest. Recently I acquired a copy of the atlas, that made it possible for me to assign proper dates to all of the plates. It was therefore thought of interest to publish these dates and at the same time to try and narrow down the dates of the text. The work itself and the series "suites à Buffon". — H. Milne Edwards's work formed part of the series "Suites à Buffon" published by the "Librairie encyclopédique de Roret" of Paris. This series consists of 84 volumes published between 1834 and 1890. It has also been indicated with the names "Nouvelles Suites à Buffon" and "Collection des Suites à Buffon", while the name "Roret's Suites à Buffon" is sometimes used to distinguish it from other series that occasionally are indicated with "Suites à Buffon". Between 1799 and 1802, namely, R. R. Castel edited an in-180 edition of the "Histoire