214 
ASPIDIACE^. 
one of the serratures of the pinnule, but terminates before reach- 
ing the spine, with which it is quite unconnected. 
It may be further observed, in comparison with the last spe- ; 
cies, that the pinnae are pinnate rather than pinnatifid ; the pin- 
nules, though sometimes connected with each other by a slender 
wing, are united to the midrib of the pinna by a very small por- 
tion of their basal diameter ; whereas in crista ta the pinnules 
are generally decurrent, and united to the midrib by their entire | 
basal diameter. The frond of spinosa is broader, its pinnae 
longer, the sixth, seventh and ninth pairs not longer than the 
first and second ; the pinnules sharper-pointed and more divid- | 
ed ; the spines longer and more obvious : still, in the more im- I 
portant characters of the scales of the stem and the structure of I 
the involucre, there is no perceptible difference ; and the dis- | 
tinctness of the two, as species, is scarcely established by the | 
trivial discrepancies which I have here noticed. | 
