66 Laws of Botanical Nomenclature. 
knowledge of facts, or from the necessity of relinquishing #) 
nomenclature that is in opposition to essential rules (art. 3, 
first paragraph, 4, 11, 15, etc. : see sect. 6). 
Art. 17. The form, the number, and the arrangement d 
names depend upon the nature of each group, according to the 
following rules. ‘ : 
Section 2. Nomenclature of the different kinds of Groups. 
§1. Names of Divisions and Subdivisions, Classes and Subclasses. 
Art. 18. The names of divisions and subdivisions, of classe 
and subclasses, are drawn from their principal characters. They 
are expressed by words of Greek or Latin origin, some similar 
ity of form and termination being given to those that designatt 
groups of the same nature (Phanerogams, Cryptogams; Mon 
cotyledons, Dicotyledons, etc.). 
Art. 19. ong Cryptogams, the old family names, such # 
Filices, Musci, Fungi, Lichenes, Alge, may be used for nam 
of classes and subclasses, | 
§ 2. Names of Cohorts and Subcohorts. 
Art, 20. Cohorts are designated preferably by the name & 
one of their principal Orders, and as far as possible with 
uniform termination. 
Subcohorts (rarely used) may be designated in the saul 
manner, 
§ 3. Names of Orders and Suborders, of Tribes and Subtribes. 
Art. 21. Orders (Ordines, Familie) are designated by the 
name of one of their genera, with the final acece (Rosaceh 
from Rosa; Ranunculacee, from Ranunculus, etc.). 
see. 22. Custom warrants the following exceptions :— 
oe _ (1.) When the Latin name of the genus from which is takes 
that of the Order ends in ~iz or -is (genitive -icis or ~idis), tt 
termination -icew, or -inee, or -idee is admitted (Salicim 
from Salia ; Tamariscinee, from Tamarix: Berberidec, 
Berberis).. ° 
(2.) When the genus from which the name is derived has# 
unusually long name, no tribe in the Order taking its appelH 
tion after the same genus, the termination in -ee is admitted | 
(Dipterocarpee, from Dipterocarpus). a1 
(3.) Some large Orders, named long since, have retained tH 
exceptional names under which they are generally known (21 
cyere, Leg uminose, Guttifere, Umbelliferce Composite, Lal 
tate, Cupuliferce, Conifere, Palmee, Graminewe ete.) a3 
: (4.) An = generic name, which has become that of a sect 
18, may be preserved as the foundation of th 
the Order (Lentibulariee, from Lentibularia; Hippocastan® 
