240 
rubbers. In the Peninsula it usually means Parameria polyneu- 
ra or P. glandulifera , but it is also used for a Hoy a which does not 
produce rubber. In Borneo it is applied to a species of Willugh- 
beia or Leuconotis. The Borneo rubber vines are at present very 
little known. Burbidge collected and made drawings of them 
when in British North Borneo, and some account of these was 
published in the Kew Bulletin for 1880, of which work I have 
been unable to procure a copy. A considerable amount of rub- 
ber is exported from Borneo, and it would be very desirable to 
obtain specimens of the plants producing it. 
Some of the recent works on caoutchouc state that the asclepi- 
adaceous plants, Calotropisprocera and C. gigantea supply part of 
the Borneo rubber. This I doubt very much, but if so, the 
amount supplied must be very small, as these plants are by no 
means abundant in this region, and thrive but indifferently, the 
climate being too wet for them. Cynanchum ovali folium has 
also been stated to produce a local rubber, but this appears to 
have originated in a mistake. The climbing Asclepiadacece may 
certainly contain caoutchouc in their latex, but their stems are 
so slender and the amount that they produce comparatively 
so small that they would hardly be worth cultivating for this 
purpose. 
Among the Apocynaceie we have a number of rubber vines 
producing rubbers of considerable value and which have long 
been in use, besides two or three trees. The following is a list of 
the species : — 
Rubber Vines. 
Flowers in short axillary cymes, fruit a berry often large. 
Willughbeia firma, Bl. Flowers white, fruit globose, soft. 
W. coriacea, Wall. ,, ,, oblong. 
W . tenui flora, Dyer. „ ,, ovoid. 
W. fiavescens, Dyer. Flower yellowish, fruit globular. 
Melodinus orientalis, Bl. Flowers white, fruit with a hard rind. 
M. coriaceus , Oliv. ,, ,, ,, 
Chilocarpus enervis , Hook. fil. Flowers orange, fruit splitting 
in two. 
Leuconotis eugeniifolius , Wall. Flowers orange, fruit pear- 
shaped. 
L. Griffithii , Hook. fil. Flowers orange. 
L. Maingayi, Dyer. ,, „ 
Flowers in panicles, terminal or axillary. Fruit a capsule with 
plumed seeds : 
Parameria glandulifera, Benth. Flowers pink. 
P. polyneura, Hook. fil. Flowers pink or white. 
Urceola elastica, Roxb. Flowers green very small. 
U. lucida , Benth. ,, ,, 
U. Malaccensis, Hook. fil. ,, 
U. Maingayi , Hook. fil. ,, „ 
U. brachysepala. Hook. fil. „ „ 
V. tornlosa, Hook. fil. ,, „ 
