ON SOUTH-AMERICAN APOCYNACEE. 203 
Species exclusee :— 
H. suberectum, G. Don, Dict. iv. p. S8. . . .= Chariomma surrecta. 
H. grandiflorum, A. DC. Prodr. viii. p. 426. . — Odontadenia grandiflora. 
H. circinalis, G. Don, Dict. iv. p. 88 . . . .  Anechites circinalis. 
H. molle, A. DO. l. c. p. 427. oo . . . .  Prestonia mollis. 
H. parviflorum, Benth. Pl. Hartw. . . . .  Temnadenia parviflora. 
H. megalagrion, Müll. Fl. Bras. xxvi. p. 170 .  Prestonia megalagrion. 
H. Reidelii, Müll. l. c. p.170 . . . . . .  Temnadenia Reidelii. 
H. annulare, A. DC. l. c. p. 428 . . . . . . Temnadenia annularis. 
H. glandulosum, A. DC. l. c. p. 427 . . . .  Echites glandulosa. 
H. glabratum, A. DC. l. c. p.427 . . . . .  Prestonia glabrata, H. B. K. 
H. Mexicana, A. DO. l. c. p. 428. . . . . .  Mitozus Mexicanus. 
H. suberectum, G. Don, Dict. iv. p. 88. . . .  Urechites suberecta. 
CYCLADENIA. 
This interesting genus was established about 1850 by Mr. Bentham in his * Plantee 
Hartwegianee * (no. 1834), upon a solitary species from California. Its stems, probably 
herbaceous, only a few inches high, rise out of a perennial thickish rhizome, as in 
Homaladenia ; the ovate very obtuse leaves, less than 1 in. long, are smooth and fleshy ; 
the inflorescence axillary and laxly racemose, the peduncle bears about 6 flowers on brac- 
teolate pedicels 6 lines long ; sepals unequal, narrow, 3 lines long, without internal scales ; 
corolla hypocrateriform, resembling that of Vinca rosea, of a purplish colour, eampa- 
nulate in the upper part of the tube, which is furnished within, at the middle, with a 
pilose ring, and 5 distinct scales placed above the insertion of the stamens, as in Hœma- 
dictyon, the mouth being quite bare; the segments broad, gibbously ovate, are half the 
length of the tube, with a sinistrorse convolution ; the included stamens have very short 
filaments; the anthers cohering in a cone by their agglutination to the clavuncle, are 
very acuminate above and biaristate at the base; the disk annular, entire, shorter than 
the 2 free ovaries, which have amphitropous ovules; style simple ; clavuncle incrassate, 
with a broad peltate basal membrane; stigmata small and terminal ; fruit unknown. 
C. humilis is a very pretty glabrous plant which I have not seen, has the habit of 
Villarsia pumila, and has no affinity with Vinca, as its stamens show. The form of the 
corolla, the presence of suprastaminal appendages, and the structure of the stamens, 
indicate its affinity towards Hemadictyon. 
The Cycladenia Harrisonii, Lem., is Odontadenia Harrisii (supra, p. 128). 
HETEROTHRIX. 
A genus established by Müller in 1860, upon a single Brazilian species, I aia 
and described by him. It was repudiated by Bentham and Hooker in the > 
Plantarum, ii, P: 724, who referred it to Echites, a genus, in their — consisting 
of a very heterogeneous group of plants; but it cannot be reconciled with that genus 
