240 
CONTRIBUTIONS TO BOTANY. 
the testa also shows, on the dexter margin of the seed, a similar 
continuous cord of the raphe ; but the intermediate integument, 
in its plicature within the groove, adheres on both sides to the 
inner tunic, till it arrives nearly at the bottom of the channel, 
where it suddenly separates from it, and crosses the groove in 
form of a diaphragm, leaving a vacant square space in the axis, 
formed by a separation of the integuments, which extends from 
the apex to the base, and upon this diaphragm is distinctly 
seen the main cord of the raphe, — an organization similar to 
to that of R. catharticus. The outer coating is of the same 
form as in R. chlorophorus, but of a different texture ; it has 
the same longitudinal open slit along the lower half of the 
sinister margin, but its edges are more or less inflected into 
the groove. Its texture is not crustaceous, but consists of a 
thick simple membrane, invested with a number of compact long 
yellow cells, disposed horizontally, and aggregated into a lax 
spongiose covering, which sometimes partially adheres to the 
endocarp. 
In Frangula vulgaris the structure is different from that of 
Rhamnus, even when the raphe is lateral, as I have shown it to 
be sometimes, in the latter genus. The seed is nearly orbicular 
and much flattened; the crustaceous covering is as thin and 
delicate as in Zizyphus, but its basal foramen is much larger, 
rounder, and more open, with two thick callous lips placed right 
and left of the axis, not anterior and posterior, as in that 
genus and in Colletia. Beneath it, and lying between it and 
the intermediate integument, there is a deposit like charred 
paper, which in most parts adheres to the external crust, but 
is separable from it, as in Colletia. On removing this, we 
find the very delicate intermediate membranaceous integu- 
ment conical towards the base, where it terminates in a 
hooked thread, as in Colletia, and from which, right and left, 
along each margin, is seen a thick white cord, both arms 
being joined in one peripherical line over the apical chalaza. It 
will be remarked that, upon the sinister side looking from the 
axis, the cord is thicker and enveloped in a yellowish in- 
crustation, which, for one-third the length of the seed, there 
adheres to the outer crustaceous coating, as was observed in 
Rhamnus chlorophorus. The embryo is perfectly flat ; the coty- 
ledons very thin and foliaceous, enclosed in an albumen of equal 
thickness ; the two internal integuments are of extreme tenuity, 
and on that account are not easily separated. This organization, 
it will be seen, greatly resembles that of Zizyphus*. 
In Zizyphus, I find the course of the raphe also peripherical. 
This structure is fully shown in Plate 33 d. 
