ON SOUTH-AMERICAN APOCYNACEX. 107 
base, with a long, gradually acute summit, 31-5 in. long, ⁄-14 in. broad, on spreading 
petioles 2 lines long; panicles terminal, thyrsoid, 4 in. long, 1 in. broad, with several 
opposite divergent branchlets 2-3 lines apart, 1 in. long, shortening upwards, again 
branching, each branchlet bearing about 6 alternate flowers, on pedicels 4 line long; 
flowers 2 lines long; segments of border puberulous inside. 
The Thyrsanthus sericeus of Sagot is referred by Bentham and Hooker (Gen. ii. 707) 
to Geissospermum. 
ROBBJA. 
This genus was first established by Prof. De Candolle in 1844, upon a Brazilian plant 
which had been previously noticed by Martius as a species of Tabernemontana. The 
genus was clearly defined by De Candolle, and well figured by Delessert, who added to 
it analytical details of the structure of the flower and the seed; but notwithstanding 
this, Dr. Müller ignored the genus, wrongly regarding the typical plant as a species of 
Malouetia. 
I have here added another species; but I will first correct a few errors in the recorded 
details, De Candolle attributes to the segments of the corolla a sinistrorse convolution ; 
but I have found this to be dextrorse, as is correctly shown in the analysis of Delessert. 
In this analysis there is an omission of the 5 scales which close the mouth of the corolla, 
which De Candolle rightly mentions. These scales are placed opposite to the segments, 
are rounded, fleshy, ciliated on their margins, and united in an annular ring. The 
anthers are enclosed for three fourths of their length within the tube, where they appear 
almost sessile; but their long filaments are agglutinated to the tube, where they form 
5 ridges covered by retrorse white hairs; upon the back of the anthers may be seen a 
line of rigid hairs. I found also the tube of the corolla puberulous within, towards its 
base. I remarked also that the inner integument of the seed is distinct, though adhering 
to the testa, and that the embryo is enveloped in thin albumen. 
l. RosB1A cestrornes, A. DC. l. c. p. 445; Deless. Icon. v. 23, tab. 52: Malouctia cestroides, Mill. 
l. c. p. 94, tab. 29. fig. 2: Tabernemontana cestroides, Nees et Mart. Nov. Act. xi. p. 83. In prov. 
Bahia et Ilheos (Blanchet 1578 et 1738) : v. s. in hb. Mus. Brit. 
This species certainly does not belong to Malouetia. It is a glabrous shrub, 6 feet 
high, with slender dichotomous branches, its axils being 132 in. apart; leaves elliptic 
. or lanceolate oblong, acute at both ends, terminated by a short obtuse acumen, sub- 
membranaceous, very glabrous, pale green above, with very fine, semi-immersed, eglan- 
dulous nerves and reticulated veins, ochraceous opake beneath, with reddish prominulent 
midrib and nerves, 14-23 in. long, 7-9 lines broad, on slender petioles 3 lines long; | 
panicles in the opposite axils, with fasciculate flowers borne on a peduncle searcely 
1 line long; pedicels slender, 4-5 lines long, with a small basal bracteole; sepals sub- 
acute, 3 line long; tube of corolla gradually swelling downwards, narrower upwards, 
With 5 small glands in the throat, it is 3 lines long, including the short campanular 
expansion of the throat; segments linear oblong, acute, 6 lines long, simply and dex- 
P 2 
