280 Notice of a Flora of North America. 
These are distinguished by characters of greater or less impor- 
tance, and, in so extremely natural a group, it follows, almost of 
course, that in some instances they are incapable of any very 
precise definition. Following the order of our authors, we have 
one, or possibly two, species of G'alatella, Cass., though appa- 
rently very rare, and even doubtful natives of the United States. 
It is remarked, that “ Galatella scarcely differs from Linosyris, 
except by the presence of (white or blue) rays; and these, ac- 
cording to Ledebour, are sometimes wanting in G. dracun- 
culoides : the two genera have also nearly the same geographical 
range. The sterile rays chiefly distinguish it from Aster $? 
Orthomeris, (species of Calimeris of authors ;) to which Aster 
nemoralis, Ait., belongs.” The genus Sericocarpus, of Nees; 
consisting of five species, is retained by Drs. Torrey and Gray, 
and it forms, no doubt, a natural group, distinguished by habit, 
the densely silky achenia, &c., but, as both they and Mr. Nuttall 
remark, so neatly connected with Aster, through A. gracilis, 
that we should, upon the whole, have preferred seeing these 
plants reunited to that genus, though, perhaps, the distinetive 
characters may be a shade more important than those of Biotia 
and T'ripolium, which are both described under different sec- 
tions of Aster, and from which, we think, they cannot conl- 
veniently be separated. Afterall, it is a matter of small mo- 
ment, practically considered, whether the subdivisions recogni 
zable.in large and very natural genera, be ranked as sections 
merely, or as independent generic forms; the sole difference 
being the value and importance of the discriminative characters 
which they respectively present; and upon these points, W™ 
vary materially in different families, the most profound botanists 
are hot unfrequently at issue. But, in such genera as Aster, Sas- 
ifraga, (nothera, and some others, in which we cannot but 
notice the continual recurrence of intermediate forms, connect 
ing the subdivisions with each other by characters possessed by 
them in common, we prefer a combination of the whole, by the 
larger and more comprehensive generic type, under which, as it 
appears to us, the sub-genera or sections may be studied with 
equal, if not greater facility. Under the several subdivisions 
the genus Aséer, Drs. Torrey and Gray enumerate, in all, ove 
‘hundred and thirty-one species, of which number eight are DoW 
scribed for the first time, whilst nine species, said to have 
