74 ILLUSTRATIONS OF 
Nierembergia resemble each other, being in the shape of 
a compressed sphere, somewhat 3-gonous, with a mammi- 
form projection at each angle; those of Nicotiana and Pe- 
tunia are of a rounded oblong cylindrical form, with 3 
longitudinal grooves, that of Vestia being similar, only of a 
nearly spherical shape. 
I have endeavoured to detect some generic distinctions 
between Cestrum and Habrothamnus ; but after careful in- 
vestigation, I cannot discover any differential characters 
either in the flower or the seed: the calyx of the latter 
is similar to that of many species of Cestrum; the corolla 
is of the same form, its lobes having in like manner a 
conduplicate estivation, 7.e. their edges being turned in 
on each side for about one sixth of their breadth, and 
adhering to the adjoining lobes by their woolly surfaces ; the 
Stamens are quite similar, as is likewise the style and 2- 
lamellar stigma; the ovarium, in like manner, is supported 
upon a short and somewhat glandular column, which when 
the corolla falls, is invested by its induviate base. I have 
also examined a capsule yet immature, in which, as in 
Cestrum, the seeds are few, rounded externally, angular 
within, and attached from a ventral hilum to the thickened 
placentation of the dissepiment, each by a short ligular 
strap, and we have the authority of Schlectendahl (Linnea, 
8, 251) to show, that the form of its embryo enveloped 
in albumen is straight, with small round flattened co- 
tyledons; characters which are all exactly those of Cestrum. 
In habit, there is certainly a difference that enables us, 
at a glance, to distinguish the one from the other, but the real 
amountof differenceis confined to the peculiarkind of articulate 
pubescence, and the crimson colour of the calyx and corolla; 
but it must be remembered, that several species of Cestrum 
from Central America, present a calyx and corolla of a deep 
orange colour, bordermg on crimson. If pubescence then 
be the only tangible character, that can hardly be sufficient 
to maintain Habrothamnus, for in such case, those species of 
Cestrum with stellate hairs, especially those that are hardly 
distinguishable from Sessea in external appearance and in 
