322 ALDROVANDA VESICULOSA. Onar. XIV, 
taining numerous crustaceans of the genus Cypris, and 
next morning many were found imprisoned and alive, 
still swimming about within the closed leaves, but 
doomed to certain death. 
Directly after reading Prof. Cohn’s memoir, I re- 
ceived through the kindness of Dr. Hooker living 
plants from Germany. As I can add nothing to Prof. 
Cohn’s excellent description, I will give only two 
illustrations, one of a whorl of leaves copied from his 
work, and the other of a leaf pressed flat open, drawn 
by my son Francis. J will, however, append a few 
remarks on the differences between this plant and 
Dionza. 
Aldrovanda is destitute of roots and floats freely in 
the water. The lcaves are arranged in whorls round 
the stem. Their broad petioles terminate in from four 
to six rigid projections,* each tipped with a stiff, 
short bristle. The bilobed leaf, with the midrib like- 
wise tipped with a bristle, stands in the midst of 
these projections, and is evidently defended by them. 
The lobes are formed of very delicate tissue, so as to 
be translucent; they open, according to Cohn, about 
as much as the two valves of a living mussel-shell, 
therefore even less than the lobes of Dionewa; and 
this must make the capture of aquatic animals more 
easy. The outside of the leaves and the petioles are 
covered with minute two-armed papille, evidently 
answering to the eight-rayed papille of Dionza. 
Each lobe rather exceeds a semi-circle in convexity, 
and consists of two very different concentric portions ; 
the inner and lesser portion, or that next to the midrib, 
* There has been much diseus- 1861, p. 146) believes that they 
sion by botanists on the homologi- correspond with the fimbriated 
cal nature of these projections scale-like bodies found at the 
Dr. Nitschke (‘Bot. Zeitung, bases of the petioles of Drosera. 
