1878.] Aspidium spinulosum and tts Varieties. 709 
From this it appears that in point of fact we have no ¢rue spin- 
ulosum as distinguished from other forms unless we choose to 
make it, and there would be no impropriety in calling it all spzv- 
ulosum, as many are disposed to do, if we did not actually find 
in nature forms possessing characters sufficiently distinctive to 
justify recognition. 
is being so we can only recognize as typical that form from 
which, in all probability, the others are most likely to have been 
derived, and to which, in connection with its special characters, 
Swartz’s description may be best adapted. 
Taking, now, the species as a whole,I find that it may be 
divided into two forms, one being glabrous beneath with perfectly 
smooth indusia, and the other being more or less finely glandular 
on the under surface with glandular indusia. : 
As there are many characters by which we can trace the 
glandular form to the smooth one, and show clearly enough that 
if it be not a good species it is at least a variation from that, we 
may by enlarging the significance of Swartz’s “rachis glabra” so 
as to embrace the smooth indusia, safely assume that the smooth 
form is Swartz’s plant. 
But as this distinction is not s apparent after the contrac- 
tion of the indusium in fruit, I have made examinations for the 
purpose of trying to find. some other character by which we 
could determine specimens with equal certainty at all times; and 
this I have SEES found in the position of the sori on the 
veins. 
Thus I find that in what I here recognize as true spinulosum 
the sori are placed on the end of the veinlet, which terminates 
within the radius of the fruit dot, while in the var. intermedium 
the sori are placed on the veinlet elow its apex, so that it passes 
through and deyond the radius of the fruit dot. 
This is a point of distinction between these two forms that has 
not been noticed heretofore by any one that I am aware of, and 
although I am not prepared to say that it is invariably the case, 
it has been so in all of the specimens that I have examined, the 
only apparent exception having been in the case of two or three 
imperfectly developed sori. 
Let us briefly review and consider the importance of the prin- 
= ¢ipal characters of spinulosum and the var. intermedium as we 
_ actually find them in nature. 
