On Sigillaria Brardii and its Variations. 235 
Weiss, in recognising the great variability of Sigillaria 
Brardw, and the numerous forms assumed by different 
portions of the species under varying conditions of growth, 
—forms to which, in many cases, specific names have been 
given, and which were supposed to belong to different 
sections of the genus,—proposes the name of Sigillaria 
mutans, under which he ineludes Sigillaria Brardw with all 
its forms and varieties. Hence Sigillaria Brardii, Brongt., 
which was originally described as Clathraria Brardw, by 
Brongniart in 1822, and which is the type of this section 
of Sigillaria, is reduced to a form of Sigillaria mutans, Weiss. 
In addition to forms, these authors name several varieties of 
the forms, which result in such combinations of names as 
Sigilaria mutans, Weiss, forma Lrardii, Brongt. sp., var. 
ottonis, Gopp. sp. 
This system of nomenclature is open to many serious 
objections. 
Notwithstanding the admitted variability of the species, 
“Brardw” was the name originally given to the first described 
specimen of the plant, and there is no dispute as to the 
plant Brongniart intended to distinguish by this name, 
therefore the substitution of the specific name “mutans” 
for “Brardw” is inadmissible, and against all laws of priority 
in nomenclature. The species always has been known, and 
must continue to be known, as Sigillaria Brardii, Bronegt., 
even although the various conditions of Sigidlaria Brardic 
vary so considerably, and embrace many forms that were 
formerly regarded as distinct species, such as Sigillaria 
spinulosa, Germar, Sigillaria rhomboidea, Brongt., Sigillaria 
denudata, Gopp., etc. When it is known that these 
are only different parts and conditions of one species, the 
distinguishing of these and other forms by distinctive names 
seems to have been carried too far in the work before us. 
To illustrate what I mean, I may mention the specimen of 
Sigillaria Brardit, Brongt., figured by Zeiller in the Bull. Soc. 
géol. d. France, 3° sér., vol. xvii., pl. xiv., fig. 1, which is given 
by Weiss and Sterzel as Sigillaria mutans, forma Brardii, 
Brongt. sp., var. typica, Sterzel+ (upper portion), while the 
1 Loc. cit., p. 132. 
