68 ON SOUTH-AMERICAN APOCYNACEA, 
are generally very large, rigid, upon short stout petioles, deeply and hoodingly fossate 
at the base. 
Ruicosrrra, nob.: Tabernemontane sectio Stenocephalium, et Ambellania (in parte), Müller. Sepala 
ovata, interdum majuscula, valde imbricata, erecta, imo in cupulam brevissimam connata, intus 
squamulis numerosis 1-2 serialibus munita. Corolla tubulosa, mediocris ; tubus imum versus sub- 
dilatatus ; segmenta tubo paullo breviora, anguste oblonga, erecta, in zestivatione simpliciter et sinis- 
trorsum convoluta. Stamina basin versus ad contractionem tubi inserta, inclusa ; filamenta brevis- 
sima; anthere acuminate, conniventes, imo breviter et obtusule bifurcate. Discus cylindricus, 
carnosus, sepe hispidulus, 5-sulcatus, ovariis paullo brevior. Ovaria 2, oblonga, libera; stylus 
brevissimus; clavuncula incrassata, cylindrica, imo peltatim membranacea. Stigmata 2, subulata, 
terminalia. 
Suffrutices Brasilienses, plerumque Amazonici, rigescentes ; rami sepius angulati et fistulosi ; folia 
oblonga, breviter petiolata ; petioli crassi imo profunde cucullatim fossati; panicul laterales, breves, 
dense pluriflore ; flores mediocres. 
1. RHIGOSPIRA QUADRANGULARIS, nob.: Ambellania quadrangularis, Müll. l. c. p. 18: Hancornia macro- 
phylla, Spruce MS. In Amazonas, v. s. in herb. meo San Carlos, Rio Negro (Spruce 3026). 
The branches are acutely 4-angled, 3 lines thick, sparsely verruculose, very fistulose, ` 
with remote axils; leaves oblong, rather acute at the base, rounded at the summit, 
rigidly chartaceous, undulately subplicate, margins subrevolute, dark reddish green 
above, opake, suleated along the broad midrib, with about 12 pairs of spreading nerves, 
arcuately conjoined at the margin, with very numerous transverse veins much reticu- 
lated, ferruginously yellow and opake beneath, the midrib very prominent and angular, 
suleate along the prominulent nerves, the surfaee spotted with large fuscous patches, 
9 in. long, 34—4 in. broad, on stout rigid petioles 1 in. long, striately angular beneath, 
channelled above, with a short, broad, hooded, basal fosset, their margins conjoined 
across the node by a prominent ridge; panicle terminal, 5 in. long, spreading above to 
the same extent, on a bare 4-angular peduncle 3 in. long, trichotomously branched 
above, branches bare at the base for 1 in., each again trichotomously and shortly divided, 
the rays severally supporting about 4 subumbellate flowers, on pedicels 2—3 lines long; 
sepals acute, $ line long; tube of corolla 3 lines long, swelling a little above the base, 
gradually narrowing to the mouth, lined within for 3 of its length with 5 densely pilose 
lines; segments linear oblong, obtuse, 3 lines long, erect, simply convoluted sinistrorsely 
and somewhat spirally in «estivation, rigid; stamens enclosed, seated in the basal con- 
traction of the tube; anthers acuminate, with 2 obtuse incurving basal prongs; disk 
cylindrical, striate, crenulate on the margin, enclosing 2 oblong ovaries of its own length; 
style very short; clavuncle oblong, incrassated with a basal peltate membrane; stigma 
shortly subulate, terminal. 
A drawing of this species, and an analysis of its flower, are shown in Plate X. A. 
2. RHIGOSPIRA VENULOSA, nob.: Hancornia macrophylla, Spruce MS.: Ambellania macrophylla, Müll. 
l. c. p. 18. In Amazonas: v. s. in herb. Mus. Brit. Panuré, Rio Uahupes (Spruce 2483). 
Miúller's specific name is not adopted, in order to avoid confusion with another plant 
