f j i
i *
detect the stipes; and the former has therefore placed it in the
genus Diatoma. I t is very rarely, however, that such fragile
plants can he observed in perfection. Captain C a r m i c h a e i .
states, that among innumerable specimens which fell under
his notice, it was hut once that he had the good fortune to find
any attached to the stipes, and only in that instance cohering
hy the alternate angles. The common state in which it occurs,
is that of the curiously combined groups already mentioned.
The central spot appears to he either orange or rose
colour; in the specimens figured by L y n g b y e , it was the latter
; in all those found hy Captain C a r m i c h a e l , the former.
That this character is liable to variation, is most probable ; for
the last-named gentleman mentions, in his letter to me, that he
has observed the spot both orange and rose colour in Achnanthes
longipes, A g . (Conferva stipitata, Engl. Bot. t. 2 4 8 8 .)
A second additional species of this small genus has been
added to the British Flora hy Captain C a r m i c h a e l , namely,
Achnanthes brevipes, A g .
F ig. 1. A.wdjiunctata, parasitic on another alga, natural size. Fig. 2 . Plants,
magnified.