294 
ROBINSON. 
but not always much more acute at the base, the apex is much more gradually 
contracted into the very distinctly longer acumen, the margins differ as the two 
original descriptions indicate, and the crenations of P. crassifolia are propor- 
tionally deeper, and the lateral nerves somewhat nearer the margin in that species. 
The most conspicuous difference is in the color of the dried leaves, which are 
darker on both surfaces of the Bornean plant, the under surface being brown or 
by means of the cystoliths somewhat golden-brown, the nerves nearly the same 
as the rest, Avliereas in P. intumescens the under surface is glauceseent, the 
nerves the same or with a reddish-brown tinge. It is possible that fuller collec- 
tions might unite these two species, but on the material at present available 
they seem to be sufficiently distinct. P. pterocaulis has also much the appearance 
of P. robinsonii Elmer, but is much smaller, the leaf-margins are different, and 
the former is trinerved and the latter triplinerved. 
Pilea johniana Stapf 1. e. 227, pi. XIX, fig. D, 17-26. 
Kinabalu, Eaviland 1391, type collection. P. humilis C. B. Rob. differs dis- ' 
tinctly by the larger, thinner, less crowded leaves. 
Pilea rigidiuscula sp. nov. 
Suffrutex (?), glaber: inflorescentiis pistilliferis quam petioli breves 
brevioribus ; perianthii lobis 3, lateralibus quam intermedius multo 
minoribus : petiolis oppositis, saepissime uno quam alter sesquilongo, 
rarius conspicue inaequilongis vel aequilongis, laminis rigidiuscule char- 
taceis, anguste ellipticis vel lanceolatis, basi angustatis obtusis retusisque 
rarissime acutis, margine supra quintam basalem partem leviter dentatis, 
apice acuminatis, saepissime triplinerviis ; stipulis parvis, orbiculari- 
triangularibus, caducis. 
Pistillate inflorescences 3.5 mm long or less, the peduncles very short 
or practically none, very sparingly branched, few-flowered; pedicels very 
short: perianth-lobes 3, the intermediate oblong-lanceolate, 0.5 to 0.6 mm 
long, the laterals broadly ovate, about 0.3 mm long; achenes compressed- 
ovoid, more or less oblique, 0.8 mm long, papillose toward the margins. 
Prom the material probably a low, branching undershrub ; leaves op- 
posite, the . petiole of one of a pair more often about one and one half 
times the length of that of the opposed leaf, sometimes very unequal or 
almost exactly equal, 2.5 to 25 mm long, the lamina rigidly chartaceous, 
narrowly elliptic to lanceolate, 3 to 6.5 cm long, 1 to 2 cm wide, almost 
equilateral except sometimes at the extreme base, the base narrowed, 
obtuse and retuse or rarely acute, the margins except toward the base 
shallowly dentate, the apex forming an acumen similarly dentate about 
6 to 8 mm long; usually definitely triplinerved, or the lateral nerves 
approaching the costa near the base and one or both continued to the 
petiole, or very rarely trinerved, the veins connecting the lateral nerves 
with the costa slender, about 10 in number but often connected with a 
slender intermediate nerve, the lateral nerves continuous to, the base of 
the acumen; upper surface of lamina dull-green with greatly crowded 
conspicuous cystoliths, under surface much paler,, with equally crowded 
