'" OBSERVATIONS ON THE GENUS HEMITELIA. 439 
West Indies; with the exception of Presl, who in his Ten- 
famen divides the genus, retaining the name Hemitelia for 
the Cape plant alone, and giving that of Cnemidaria to 
the West Indian ones, except H. multiflora, which he 
refers to the genus Alsophila. In doing this, Presl has 
certainly not acted in accordance with the rule which ought 
to guide botanists when they find it necessary to divide a 
genus; viz. that the old name should be retained for the 
mass, and not for a single species, as is the case in this 
instance. Any one who reads attentively the observations of 
Mr. Brown, quoted above, must perceive that he intended 
the name Hemitelia to be applied to the West Indian group 
of which H. horrida is the type. Presl, in referring H. mul- 
liflora to Alsophila can hardly have had an opportunity of ex- 
amining its fructification, or he would never have placed it 
in a genus which is characterised, by himself, as having “ sori 
nudi.” Through the kindness of Mr. Brown, I have been 
allowed to examine a specimen in the Herbarium of the 
British Museum, and I find it has as perfect an involucrum, 
and quite of the same nature as that of the true species of 
Hemitelia, from which it, however, differs in having tripin- 
nate fronds, and simple veins, and, consequently agreeing in 
this latter respect with some species of Alsophila. In H. 
Capensis Y also find a true involucrum surrounding the 
receptacle, narrower than that of H. multiflora, longer, acu- 
minated, and often a little lacerated. "With the persistent 
involucrum of Hemitelia, this species has also the habit of 
Alsophila, and, consequently cannot be separated from H. 
multiflora : wherever the one is placed the other must go also. 
The only difference between them is that, in H. Capensis, the 
sorus is situated only a little way above the base of the 
simple veins, while in H. multiflora it is placed about the 
middle of it. As they are very distinct in habit and venation 
from Hemitelia, and from Alsophila, as at present constituted, 
in haying a true persistent indusium surrounding the base of 
the receptacle, I propose to constitute of them a distinct 
genus. Since Presl’s genus Hemitelia cannot be retained, that 
