The neglected generic and specific names proposed by Palisot de Beauvois in 1822 (between 9 and 16 September 1822), in his posthumously published work Muscologie ou traité sur les mousses, are discussed. Perisiphorus P. Beauv. is considered to be a nomen nudum synonymous with Hedwigia P. Beauv. and accordingly the binomial P. ciliatus (Hedw.) P. Beauv. is invalidly published. The monotypic genus Apocarpum P. Beauv. is congeneric with Coscinodon Spreng. and its only species, A. commune P. Beauv., is conspecific with C. cribrosus (Hedw.) Spruce. Apocarpium P. Beauv. ex Desv. of 1824 and Acrocarpium P. Beauv. ex Margad. of 1968 are orthographic variants of Apocarpum. The generic name Fusiconia P. Beauv. is illegitimate because it comprises the type of Gymnocephalus Schwägr., and both are rejected names. For four new species only detailed illustrations, with analysis in the captions to the plates, were provided. Their identities are as follows: Dicranum polyanthum P. Beauv. is Cynodontium polycarpon (Hedw.) Schimp.; Bryum sclerodon P. Beauv. is Octoblepharum albidum Hedw.; Cyathophorum heterophyllum P. Beauv. is C. bulbosum (Hedw.) Müll. Hal.; and Climacium europaeum P. Beauv. is C. dendroides (Hedw.) F.Weber & D. Mohr. Leskea serpens (Hedw.) P. Beauv. var. repens (Brid.) P. Beauv. is accepted as a new nomenclatural combination and this varietal name is considered to be a synonym of Herzogiella seligeri (Brid.) Z. Iwats. Cecalyphum fertile P. Beauv. ex Wijk, Margad. & Florsch. is an invalid name published by error in the Index muscorum.