35 



g) Algae, 1753 (Linnaeus, Species Plantarum^ ed. 1). Exceptions: Nosto- 

 caceae homocysteae, 1891 — 93 (Gomont, Nostocaceae homocysteae)\ Nostocaceae hetero- 

 cysteae, 1886 (Bornet et Flahault, Nostocaceae heterocysteae)\ Desmidiaceae, 1848 

 (Ralfs, British Desmidiaceae); Oedogoniaceae, 1900 (Hirn, Monographie und Ikono- 

 graphie der Oedogoniaceen). 



h) Myxomycètes, 1753. 



It is agreed to associate genera, the names of which appear in Linnaeus's 

 Species Plantarum, ed. 1., with the descriptions given of them in the Genera 

 Plantarum, ed. 5. (1754). 



Art. 20. However, to avoid disadvantageous changes in the nomenclature 

 of genera by the strict application of the rules of nomenclature, and especially of the 

 principle of priority in starting from the dates given in art. 19, the rules provide a 

 list of names which must be retained in all cases. These names are by preference 

 those which have come into general use in the fifty years following their publication, 

 or which have been used in monographs and important floristic works up to the 

 year 1890. 



For the guidance of palaeobotanists a double list is provided: 1® a list of 

 generic names of recent plants, duly published and generally admitted, which coincide 

 with older generic names in palaeobotany; 2° a list of generic names of fossil plants, 

 duly published and generally admitted, which coincide with older homonyms of recent 

 plants which have lapsed into synonjnmy, in order to prevent the latter being used 

 again. The Usts form an appendix to the rules of nomenclature^). 



Section 3. Nomenclature of the different kinds of groups. 



§ 1. Names of groups above the family. 



RecommendatioiiSi The following suggestions as to the nomenclature of groups of higher 

 rank than the family will tend to clearness and uniformity. 



H. Names of divisions and subdivisions, of classes and subclasses are taken from one of 

 their chief characters. They are expressed by words of greek or latin origin, some similarity of 

 form and termination being given to those which designate groups of the same nature. 



Examples: Angiospermae, Gymnospermae ; MonocotyUdoneae; Dicotyledoneae ; Pteridophyta ; 

 Coniferae. Among Cryptogams old family names such as Fungi, Lichenes, Algae, may be used for 

 names of groups above the rank of family. 



m. Orders are designated preferably by the name of one of their principal families, with 

 the ending -ales. Suborders are designated in a similar manner, with the ending -ineae. But other 

 terminations may be retained for these names, provided that they do not lead to confusion or error. 



Examples of names of orders: Polygonales (from Polygonaceae), Urttcales (from Urticaceae), 

 Glumiflorae, Centrospermae, Parietales, Tubiflorae, Microspermae, Cantortae. Examples of names of 

 suborders: Bromeliineae (from Bromeliaceaè), Malvineae (from Malvaceae), Tricoccae, Enantioblastae. 



§ 2. Names of families and subfamilies, tribes and subtribes. 

 Art. 21. Families {familiae) are designated by the name of one of their 

 genera or ancient generic names with the ending -aceae. 



1) The elaboration of this double list has been reserved for the Congress of 1915. 



5* 



