CONTRIBUTIONS TO BOTANY. 
ment of the floral envelopes, though generally similar in both 
sexes, does not exist in Cissampelos, Cyclea, Clypea, Antizoma, 
and Stephania, where, in the female flowers, many of the parts 
are wanting, being sometimes reduced to a single sepal and only 
one minute petal, while the male flowers exhibit the usual num- 
ber of sepals. 
The petals, usually six in number, are in the form of small 
scales or fleshy leaflets originating from the torus. Little notice 
was taken of them formerly, as they were looked upon as a mere 
nectary ; but they are now universally regarded as real petals, 
though of minute size ; in some few instances they are entirely 
wanting, as in Anamirta, Coscinium, Abuta, Anelasma, Batschia, 
Triclisia, Syrrhonema, and sometimes in Calycocarpum : in Fi- 
braurea they are apparently deficient, but are probably conflu- 
ent with the filaments, seemingly as if wrapped round them : in 
many of the genera the petals, though quite free, are found, in a 
similar manner, with their margins involute and embracing the 
filaments. 
The stamens, especially in the male flowers, by their form and 
position, afford constant and valid characters ; they are usually 
equal in number to the petals, opposite to them, and generally 
in two distinct approximated whorls. In most instances they 
are all quite free ; but sometimes the three outer stamens are 
free, while the others are partially monadelphous in the centre ; 
at other times they are all more or less compactly united into a 
simple central column. They are usually as long as the petals, 
frequently double their length. The anthers are generally two- 
lobed, the lobes being often separated by a connective, which is 
continuous with the filament •, sometimes they are combined to- 
gether without the intervention of any connective, and partially 
sunk in the apex of the filament, or often approximated and 
dorsally affixed upon fit ; generally these lobes open by a longi- 
tudinal suture, but they sometimes burst by a transverse, verti- 
cal, or oblique fissure. In the Cissampelos group, the stamen 
consists of a single filamentous column supporting a horizontal 
peltate disk bearing on its margin four, six, eight, or more 
anther-cells, combined in an annular form, which burst on their 
'outer edge, like the indusium of some ferns. In other cases 
several anther-cells are combined into a globular mass, and are 
either sessile on the torus or supported on a central column. 
In many cases each anther-cell appears bilocellate, owing to a 
prominent septum that almost or completely divides it. These 
great varieties in the disposition and structure of the stamens 
are constant in each genus, and may be trusted as good discri- 
minating characters. 
In the female flowers we generally find the same number and 
