42 



work containing the name or combination of names is regarded as correct. On and 

 after January V\ 1908, the date of publication of the latin diagnosis only can be 

 taken into account in questions of priority in the case of recent plants; in the case 

 of fossil plants, on and after January 1^*, 1912, it is the date of simultaneous publi- 

 cation of the latin diagnosis and a figure. 



Examples. — Mentha foliicoma Opiz was distributed by its author in 1832, but the name 

 dates from 1882 (published by Déséglise Menth. Op. in Bull. soc. étud. scient. Angers, 1881 — 1882, 

 210); Mentha bracteolata Op. Seznam, 65 (1852) without description, takes effect only from 1882, 

 when it was published with a description (Déséglise 1. c. , 211). There is some reason for 

 supposing that the first volume of Adanson's Families des Plantes was published in 1762, but in 

 absence of certainty the date 1763 on the title-page is assumed to be correct. The different parts of 

 Willdenow's Species Plantarum were published as follows: vol. I, 1798; vol. II, 2, 1800; vol. Ill, 1, 

 1801; vol. Ill, 2, 1803; vol. Ill, 3, 1804; vol. IV, 2, 1806; and not in the years 1797, 1799, 1800, 

 1800, 1800 and 1805 respectively, as would appear from the title-page of the volumes: it is the 

 earlier series of dates which takes effect. — The third volume of the Prodromus florae hispanicae 

 of Willkomm & Lange, the title-page of which bears the date 1880, was published in four parts, 

 pp. 1—240 in 1874, pp. 241—512 in 1877, pp. 513—736 in 1878, p. 737 to the end in 1880, and 

 it is these dates which take effect. 



Recommendations. Botanists will do well, in publishing, to conform to the following 

 recommendations : 



XVin. Not to publish a name without clearly indicating whether it is the name of a 

 family or a tribe, a genus or a section, a species or a variety; briefly, without expressing an opinion 

 on the nature of the group to which they give the name. 



XVIIIbis. When publishing names of new groups to indicate carefully the subdivision 

 which is regarded as the type of the group: the typical genus in a family, the typical species in a 

 genus, the typical variety or specimen in a species. This precaution will obviate difficulties of 

 nomenclature if at some future time the group in question becomes broken up. 



XIX. To avoid publishing or mentioning in their publications unpublished names which 

 they do not accept, especially if the persons responsible for these names have not formally authorised 

 their publication (see Eec. XIV, e). 



XX. When publishing names of new groups in works written in a modem language (floras, 

 catalogues etc.) to publish simultaneously the latin diagnoses and in palaeobotany also the figures, 

 which will make the names valid from the point of view of scientific nomenclature. 



XX bis. In view of the special difficulties presented by the identification of fossil plants, 

 to give, in addition to the latin diagnosis a detailed description in french, english, german or Italian. 



XXter. In describing new groups of lower Cryptogams, especially among the Fungi or 

 microscopic plants, to add to the description a figure or figures of the plants, with details of 

 microscopic structure, as an aid to identification. 



XX quat- The description of parasitic plants should always be followed by the indication 

 of the hosts, especially in the case of parasitic fungi. The hosts should be designated by their 

 latin scientific names and not by popular names in modern languages, the signification of which is 

 often doubtful. 



XXI. To give the etymology of new generic names and also specific names when the 

 meaning of the latter is not obvious. 



XXn. To indicate precisely the date of publication of their works and that of the placing 

 on sale or the distribution of named and numbered plants when these are accompanied by printed 

 diagnoses. In the case of a work appearing in parts, the last published sheet of the volume should 

 indicate the precise dates at which the different fascicles or parts of the volume were published, aa 

 well as the number of pages in each. 



