258 CODE OF BOTANICAL NOMENCLATURE 
persons, Greene and Green, may be maintained in the same genus; vr- 
ginicus, virginianus and virginiensis, oreganus and oregonensis, Hookeri 
and Hookerianus, can not be maintained in the same genus. 
Canon 17. A name is rejected when there is an older valid name 
based on another member of the same group (metonym). 
EXxAMPLES.—Meibomia Heist. ex Adans. Fam. Pl. 2: 509 (1763), is based 
on Hedysarum canadense L. Sp. Pl. 748, and Desmodium Desv. Jour. de Bot. 
Desmodium is to be rejected; Boletopsis P. Henn. Nat. Pflanzenf. 11**: 194 
(1899), cannot stand as a genus to include a section bearing the name Boletinus 
Kalchb., the latter having en ge a as a genus in 1877; Sisymbrium 
aap L. Sp. Pl. 659 53)> rium Sinapistrum Crantz, Stirp. 
r. ed. 2, 52 (1769), and ile ae ate Jacq. Coll. 1: 70 “(1786), 
rome different types, but if these are regarded as atta to the same species, 
the two later names are metonyms of that of Linnae 
Canon 18. A name is rejected when there is an older valid name 
based on the same type (typonym). 
ExaMPLes.—Afiegia Pers. Syn. 1: 101 (1805), is a typonym of Arunai- 
naria Michx. Fl, Bor. Am. 1: 1803), both parti based on the same spe- 
cies; Asplenium Vincentis Christ, Bot. Jahrb. 24: 109 (1897), is a typonym of 
A. Guildingit Jenm. Gard. Chron. III. 70 hoes both being based on 
H. H. Smith’s 20. 1746 from St. Vince 
Canon 19. A name is rejected when the natural group to which 
it applies is undetermined (hyponym). 
(a) A specific or subspecific name is a hyponym when it has 
not been connected with a description identifiable by 
diagnostic characters or by reference to a type specimen, 
figure or locality. 
EXAMPLES. —Gentiana hybrida Raf. Med. Rep. II. 5: 353 (1808); 
isa hyponym, as no diagnosis is published ; Lechea furfuracea Raf. New 
Fl. Am. 1: 92 (1836), is a hyponym, as its description is not identifiable. 
(6) A generic or subgeneric name is a hyponym, when it is 
not associable, at least by specific citation, with 4 
binomial species previously or simultaneously published ; 
or when its type species is not identified. 
EXAMPLES.—Adodendrum Necker, Elem. 1: 214 (179°); and Cale- 
stam Adans. Fam. Pl. 2: 446 (1763), are hyponyms, because their authors 
neither named a binomial species nor cited a species which had pre- 
viously received a binomial name; Vudilus Raf. Atl. Jour. 176 (1833), . 
hyponym, as its type species, XN. paradoxus, has not been identified. 
