Mr. J. Miers on some of the Heliotropiese. 123 



two opposite bipartite parietal placentae, each fork bearing a 

 single ovule, as in jEgijphila and Amerina. If these figures 

 be correct, as there is no reason to doubt, these species cannot 

 belong to Ehretia^ or else the characters of the genus have 

 been erroneously defined, and the tribe itself has been placed 

 in a wrong family. These discrepancies show that we have 

 yet much to learn in regard to the Ehretiece. If we hold 

 Beurreria still in doubt, as well as Amerina j for the reasons 

 before given, there will remain only Ehretia itself to represent 

 the tribe; and this offers so many anomalous characters that 

 DeCandolle considered it must ultimately be divided into se- 

 veral genera, of which he traced the outlines in Beurreria^ 

 Carmona^ Xerodema^ and Menais. Xerodema has been shown 

 to be identical with Rhahdia^ a Brazilian genus minutely and 

 accurately described by Prof, von Martins in his ^ Nova 

 Genera,' and since figured by Sir Wm. Hooker (Icon. 823). 

 This construction, of a 1-locular ovary, with two opposite 

 2-lamellar placentae bearing an ovule on each of their reflected 

 margins, and a fruit with four nucules, each with a longitu- 

 dinal open slit leading into two cells, is quite at variance with 

 the structure that has been attributed to Ehretia and its allied 

 genera. I will offer some observations upon Rhahdia and 

 Cortesia under separate notices. 



The following is a synopsis of the genera of the Helio- 

 tropiecB :— 



1. Fructus baccatus ; albumen distinctum. 



A. Pvrenae 2, singulse 2-loculares. 



a. Embryo rectus ; stamina inchisa ; stylus brevis ; 



stigma latum, bre^-iter 2-lobum Tournefortia. 



B. Pyrenfe 4t, singulse 1-loculares. 



b. Embryo lunatim curvatus; coroUae laciniae subu- 



latae ; stamina inclusa ; stylus longiusculus ; 



stigma majusciilum, apice conico, piloso Messerschmidtia. 



2. Fructus exsuccus ; albumen distinctum, aut nullum. 



C. Pyrenae 2, singulte 2-loculare8 5 stamina inclusa, 



c. Stigma breve, vix di visum ; albumen nullum .... Heliophytum. 



d. Stigma magnum, elongatum, profunde 2-fissum ; 



albumen distinctum Cochranea. 



D. Pyrense 2, singulse 2-loculares. 



e. Stamina longe exserta ; stylus tenuis ; stigma te- 



nuiter 2-fidum Tiquilia. 



E. Pjrrenai 4, singulae 1-loculares, 



/. Antherse apice papilloso cobaerentes ; stylus brevis 

 aut subnuUus ; stigma magnum ; flores interdum 

 solitarii et axillares Schleidenia. 



g. Antherae glabrae, oblongae, liberae ; stylus medio- 

 cris; stigma magnum; flores in spicas longas 

 curvatas temiinales, 1-laterales Heliotropium. 



h. Antherae glabrae, globosae, liberae ; stylus simplex, 



2-fidus J flores axillares, solitarii Coldenia. 



