150 CONTRIBUTIONS TO 



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 aestivation, i. 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 m 

 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 

 amount of difference is confined to the peculiar kind 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, bordering 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 



