400 NATURAL HISTORY OF PLANTS. 
Choisya has larger flowers than Geijera, very analogous to those 
of Boronia and Diosma, from which they cannot be nicely dis- 
tinguished so long as the seeds are unknown. The five petals are 
contorted; the androceum is diplostemonous, and the five inde- 
pendent ovaries biovulate; while the leaves are opposite and trifo- 
Peltostigma ptelevices. 

Fie, 443. Fra. 444. 
Flower. Longitudinal section of flower (2). 
liolate, and the flowers disposed in biparous cymes.  A/edivosma 
(figs. 439-442) has also opposite leaves, but simple and tolerably 
large tetramerous flowers, with contorted or imbricated petals. The 
androceum is diplostemonous, and the carpels independent in the 
ovary. Platydesma may perhaps be defined: a Medicosma, with 
ovaries not completely independent of each other, and each including 
from four to six biseriate ovules. Dutaillyea, a New Caledonian 
plant, has the same tetramerous flowers as the two preceding genera, 
with a single four-celled ovary, an isostemonous androceum, and 
opposite trifoliolate exstipulate leaves.’ 

ae = 
with these leaves are indicated, represented by The descendent monospermous seed contains a 
anthers “sessile cuneiform,-united at the base large fleshy embryo, with plano-convex coty- 
with extrorse dehiscence,” two-celled, In the  ledons and short radicle, By these characters 
female flowers there are two independent carpels the plant would seem as though it might be 
described as superposed to the sepals; each is considered as a reduced type of Zanthoxylon. 
formed of a one-celled ovary, surmounted by a ‘The only species known is D. excelsa (D, mada- 
short style immediately dilated into a large head,  gascariensis W.).—Anthæa excelsa Non. & Dur.- 
like a crest rolled up, quite covered with a stig- Tir., loc. cit. — Didymomeles madagascariensis 
matic papilla, and traversed by a middle groove SPRENG. 
descending by the internal edges of the ovary. ' The two genera Astrophyllum and Peltos- 
Corresponding to this border is a placenta, sup-  //gma (figs. 443, 444) are doubtfully placed here. 
porting a descending ovule with exterior and ‘The former because the only flower which we 
superior micropyle prolonged into a sinuous tube, have been able to study did not belong with cer- 
dilated at the apex. The fruit is described as tainty to the specimen accompanying it; it may 
formed of one or two drupes with a bony stone. be thus defined:—A Zanthowylon with squami- 
