1907] On the Vienna Rules of Nomenclature 47 
of the genera which at that time contained only four species, and reserved 
the name Convolvulus for the other genus which contained a much larger 
number of species. —In the same way Salisbury (in Trans. Linn. Soc. VI, 
317 [1802]), in separating Erica vulgaris L. from the genus Erica, under the 
name Calluna, kept the name Erica for the large number of species left. 
Art. 46. When two or more groups of the same nature are united, 
the name of the oldest is retained. If the names are of the same 
date, the author chooses, and his choice cannot be modified by sub- 
sequent authors. 
Examples. — Hooker f. and Thomson (Fl. Ind. p. 67 [1855]) united the 
genera Wormia Rottb. and Capellia Bl.; they gave the name Wormia to the 
enus thus formed because the last name dates from 1783 while Capellia 
ates from 1825. — In case of union of the two genera Cardamine and Dentaria, 
which were founded at the same time by Linnaeus (Sp. Pl. ed. 1, p. 653 and 
654 [1753]; Gen. Pl. ed. 5, n. 726, 727) the collective genus must be called 
Cardamine because that name was chosen by Crantz (Class. Crucif., p. 126. 
[1769], who was the first to suggest the union. 
Recommendations. 
XXVI. Authors who have to choose between two generic names should 
note the following recommendations: 
1. Of two names of the same date to prefer the one which was first accom- 
panied by the description of a species. 
2. Of two names of the same date, both accompanied by descriptions of 
spares, to prefer the one, which, when the author made his choice, included 
the larger number of species. 
3. In cases of equality from these various points of view to prefer the more 
correct and appropriate name. 
XXVII. en several genera are united as subgenera or sections under 
one generie name, that subdivision which was first distinguished or described 
may retain its name (ex.: Anarrhinum sect. Anarrhinum; Hemigenia sect. 
Hemigenia), or be preceded by a prefix (Anthriscus sect. Eu-Anthriscus) or 
followed by a suffix (Stachys sect. Stachyotypus). These prefixes or suffixes 
lapse when the subdivisions are raised to generic rank. 
XXVIII. When several species are united as subspecies or varieties under 
a collective name, that subdivision which was first distinguished or described 
may retain its name (ex.: Saxifraga aspera subsp. aspera) or bear a prefix 
(Alchemilla alpina subsp. eualpina) or be designated by some customary title 
(normalis, genuinus, typicus, originarius, verus, veridicus etc.). These prefixes 
or terms lapse when the subdivisions are raised to specific rank. 
Art. 47. When a species or subdivision of a species is divided into 
two or more groups of the same nature, if one of the two forms was 
distinguished or described earlier than the other, the name is retained 
for that form. 
Examples. — Genista horrida DC. Fl. Franc. IV. 500 was divided by Spach 
B" Ann. Sci. Nat. ser. 3, II., 253 [1844]) into three species: G. horrida DC., 
. Boissieri Spach and G. Webbii Spach; the name G. horrida was rightly 
kept for the earliest described form, that described and figured by Vahl. and 
Gilibert.— Several species (Primula cashmiriana Munro, P. erosa Wall.) 
have been separated from Primula denticulata Sm. (Exot. Bot. IT, 109, tab. 
114), but the name P. denticulata has been rightly kept for the form which 
Smith described and figured under this name. 
