to which the Heveas form part, I will but briefly quote a few exam- 
ples of other trees whose milk is useful. The Apocynaceae, the 
Sapotaceae, the Clusiaceae, the Asclepiadaceae and others, are 
represented by useful lactiferous plants, among them the Couma 
a tills, Mart. Couma macrocarpa , Barb- Rod. Plumeria phagede- 
nica , Muell. Mimusops elata, Fr. Allem. Calophyllum Brasiliense, 
Mart. Platonia insignis, Mart. Moronobia coccinea , Aubl. Sim - 
phonia global if era, Linn. f. and many olhers, whose milks produce 
rubber, gutta pereha and resin. 
From these families spring the Landolphias, the Castilloas, the 
Tabernaemontanas, the Ficus, the Urceolas and other exotics, all 
of which have been of some benefit to the rubber industry in Asia, 
in Africa and in America. 
Various are the sp'ecies of Seringueiras in the valley of the 
Amazon, but these are known only to the more intelligent of the 
aborigines, some of whom are experts in spotting their differences. 
Scientifically ten species have been described, yet, not all these 
present the same properties which will all be defined solely by 
their leaves, since by this means, the uninformed will probably be 
able all the better to distinguish them, thus omitting their floral 
characters, not always within the power of every one to observe. 
We now proceed to describe the general shape of the leaves and 
their position, by their details, separating the species as follows: — 
1. H. SPRUCEANA, Mull. D'Arg. Leaflets oblong-obovate, ob- 
tusely acuminate, sharp at the base, above shining, below glaucous- 
tawny with glabrous nerves conjointed to small petiolules on one 
petiole with five glands at the apex, and ofo m , 09-0™- 12x0™ 
05, 06 in length. 
2. H. DISCOLOR, Mull. D'Arg. Leaflets similar to the species 
above, but rigidly membranous, opaque, oblong-elliptical or oblong- 
obovate, with the nerves pubescent. 
3. H. MEMBRANACEA, Mull. D' Arg. Leaflets membranous, 
lanceolate-obovate, straight at base, acuminate, glabrous on both 
sides, dark green above and glaucous-tawny below, of o 08-0 m < 
15x0™. 035-0^055 in length. 
4. H. PAUCIFLORA, Mull . D'Arg. Leaflets coriaceous lanceo- 
late-obovate, obtusely acuminate, with the base acute, above 
smooth, below glaucous, glabrous, of o m , ro-o*«. r 2 x o m . 05-0 m , 
08 in length. 
5. H. Rigidifolia, Mull. D’Arg. Leaflets coriaceous, with 
margins recurved, of same length as petioles, oblong elliptical, 
acuminate with the base acute, rigid, above smooth and shining, 
beiow glaucous, with the secondary nerves prominent and of o 
09-0 m , oi2 x om. 04-0 05 in length, 
6 H, NlTlDA, Mull. D’Arg. Leaflets with the petioles bi- 
glandular at apex, oblong-elliptical, very shining, acuminate, rigid, 
glabrous, pale below and of o m , 13-om, 18 x m, 055-0™, 08 in 
length. 
7. H. BENTHAMIANA, Mull. D’Arg. Leaflets membranous, 
oblOng-obovate, of the size and form of Spruceana , pubescent and 
below tawny-glaucous. 
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