280 POSITION OF THE GENERA HYDROCOTYLE, ETC. 
the name of P. horridum), and by Willdenow and Hooker to Aralia 
(under those of 4. occidentalis and A. erinacea). 
I have not yet gone over all the Umbelliferous genera suspected 
of a valvate corolla, but I shall do so before finally publishing a paper 
Lhave been preparing on the Araliacee, and for the present confine 
myself to transferring to Araliacee, Hydrocotyle, Diplepsis, Pozoa, As- 
trotricha, and Horsfieldia. 
n their paper on Araliacee, Decaisne and Planchon* have stated the 
corolla of a few species of Aralia and Punazx to be imbricate. They 
probably. employed the term in a loose way, for in Panax quinque- 
olium, P. trifolium, Aralia racemosa, and the plants of which they 
are the generic type, the corolla is quincuncial, that is to say, of the 
five petals, the two external ones overlap two of the internal ones, and 
the fifth is overlapping on one edge, and overlapped on the other. 
II. Opa, Lour. 
The genus Opa has been referred to Syzygium of Geertner by De 
Candolle following up a hint thrown out by Willdenow, in his edition 
of the ‘ Flora Cockiuchinenets, Loureiro described two species, Opa 
odorata and O. Metrosideros, authentic specimens of both of which are, 
preserved at the British Museum. O. odorata is a true Syzygium 
(S. odoratum, De Cand., S. lucidum, Gærtn.); and, as the genus 
Syzygium was published in 1788, and Opa in 1790, the name d 
enjoys the right of priority. 
It is different with Opa Meterosideros, which De Candolle refers with 
a mark of doubt to Syzygium, but which is no Myrtacea at all. 
Loureiro’s description and two authentic specimens prove it to be 
identical with Rhaphiolepis Indica, Lindl., and as Rhaphiolepis is p 
most recent name it will have to be suppressed. 
m Opa, Lour, Fl. Cochinch. excl. sp.— Rhaphiolepis, Lindl. Bot. Reg. 
468. 
1. O. Meterosideros, Lour. Fl. Cochinch. et Willd. P 318, excl 
syn. Rumph.—Rhaphiolepis Indica, Lindl. Bof. Reg. t. 4683 bau 
Mag, t. 1726 ; Benth. Fl. Hongkong. p. 167. R. rubra, Phiostemon, 
et edil Lindl. Coll. Bot. et Bot. Reg. t. 652. Syzygium (P) Metro- 
sideros, De Cand. Prod. iii. p. 261.—China and Cochinchina. à 
* “ Revue Horticole,’ 1854. 
