AMERICAN CODE OF BOTANICAL NOMENCLATURE 175 
Raf. Jour. Phys. 89: 105 (1819), of Zorreya Spreng. Neue Entdeck. 2: 
12t (1821), and of Zorreya Eat. Man. ed. 5, 420 
(c) Similar names are to be treated as homonyms only when 
they are mere variations in the spelling of the same word ; 
or in the case of specific and subspecific names, when they 
differ only in pe or genitive termination. 
EXAMPLES. — Penici//us and pecan Callitriche and Calothrix, 
Pterigophyllum and seen, may be maintained ; Cyathophora and 
yathophorum, Asterocarpus and Astro Aone. can not be maintained. 
| anu and Greenii, named for different persons, Greene and Green, may 
be maintained in the same genus; virginicus, 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). 
ExampLes,— Aeibomia Heist, ex Adans. Fam. Pl. 2 : 509 bed bs is sees 
on Hedysarum canadense L. Sp. Pl. 748, and Desmodium Desv. Jou 
pt ae 2 (1813), is typified Hedysarum asperum Poir. Encycl. S as 
408 (1804), consequently if these species are regarded as congeneric the name 
Paes tae is to be rejected ; ee P. Henn. Nat. Pflanzenf. 1'**: 194 
(1899), cannot stand as a genus to include a sae bearing the name Bo/etinus 
Kalchb., the latter having been caine as a genus in 1877; Sisymbrium 
altissimum 1. Sp. Pl. 659 (1753), Sesymbrium Sinapistrum Crantz, Stirp 
Austr. ed. 2, §2 (1769), and Sisymbrium pannonicum Jacq. Coll. 1: 70 (1786), 
have different types, but if these are regarded as belonging to the same species, 
the two later names are metonyms of that of Linnaeus. 
Canon 18. A name is rejected when there is an older valid name 
ages on the same type (typonym). 
XAMPLES.— Miegia Pers. Syn, 1: 101 (1805), is a typonym of Arundi- 
naria set Fl. Bor. Am. 1:73 (1803), both being based on the same spe- 
cies; Asplenium Vincentis Christ, a oe 24: 109 (1897), isa typonym of 
A. Guildingii Jenm. Gard. Chron. IIT. net (1894), both being based on 
H. H. Smith’s xo. 73746 from St. spo 
Canon 1g. A name is rejected heh 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, 1 identifiable by 
diagnostic characters or by reference to a type specimen, 
figure or locality. 
EXAMPLES. — Gentiana hybrida Raf, Med. Rep. Tt. 6 :353 ( aont 
is ei cian as no diagnosis is published ; Lechea furfuracea Raf. 
1. Am. 1 : 92 (1836), is a hyponym, as its description is not Dace 
(4) A ei or subgeneric name is a hyponym, when it is 
not associable, at least by specific citation, with a 
