220 
CONTRIBUTIONS TO BOTANY. 
shaped vesicular membranaceous tube, originating at its base 
in the extremely small torus, and terminating at its summit in 
continuity with the persistent style, where it also unites with 
the pericarpial covering of the fruit ; it has four distinct longi- 
tudinal cords or bundles of spiral threads terminating below the 
style, some of which adhere to the fungous lines seen upon the 
nucules ; this tube touches the smooth ventral faces of the 
nuts, without absolutely adliering to them ; there is no trace 
of any basal gynobasic attachment of the nuts, which do not 
even touch the torus. 
It has been already noticed {supra, p. 192) that this struc- 
ture cannot be reconciled either with the Heliotropiacece or 
with Ehretiacece. under the conditions hitherto supposed to 
exist. The reality of the organization above described is, 
however, unquestionable, being clearly illustrated by Von 
Martins in the work referred to, in like manner depicted by 
Dr. Wight (Icon. 1385) and by Sir Win. Hooker (Icon. 823). 
In searching for a parallel structure, we naturally come upon 
the Hydrophyllaeem, with which Rliabdia agrees in having a 
deeply 5-cleft calyx, a campanula!' corolla with a 5-lobed 
border, five equal subexserted stamens affixed near the bottom 
of the tube of the corolla, 2-lobed anthers, a simple style 
with a 2-lobed stigma, a superior 1-celled ovary with a parietal 
placentation, as before explained, and albuminous seeds en- 
closing an embryo with a superior radicle : but here the ana- 
logy ceases ; for it differs in its suffruticose virgate growth, the 
stems crowded with simple, almost sessile leaves, the want of 
scales in the tube of the corolla, and in the totally different 
structure of the fruit. 
In regard to its real affinity, it is clear that the peculiar 
placentation just deS'cribed would remove it far from the Ehre- 
tiacece, under the supposition that the carpical structure of the 
latter accorded with the rule that has been hitherto imder- 
stood : but it is quite otherwise ; for a more searching exami- 
nation into the structoe of Ehretia and its congeners has 
revealed the fact, which I shall be able to demonstrate, that 
there is little difference in their placentation from that of 
Rhabdia and Cortesia. Consequently Rhabdia will still re- 
main a member of this family. 
There is, however, a wide distinction between Ehretiacece 
and Borraginacece {Borragece of De Candolle), the latter of 
which ought certainly to stand as a family distinct from all the 
tribes associated with them in the ‘ Prodi'omus,’ because they 
differ essentially in the peculiar gynobasic disposition of the 
carpels. By adopting as a basis of arrangement the various 
modes of organization of thv carpels, the Hydrophyllacece 
