16. 
16a. 
18a, 
19a. 
20. 
20a. 
21. 
yellow with maroon dots; sepals and petals 
ovate-oblong, acute... . ; . 2 2. « « O. atrovirens 
Inflorescence with short ecnelieds ncn white, 
sepals and petals linear-oblong, obtuse . . . . . O. latifolia 
Blades of leaves narrow, linear . . . . ..... =... 14 
a. Blades of leaves broad, ovate to elliptic. . . ..... .17 
Leaves long-acuminate, lorate, 50 cm. or more long, 
gradually tapering to pseudobulb without a distinct 
Wellgle 4. 9 40% % « & & &'% ce eae oo & OD Perse 
Leaves acute or obtuse, linear- sieve: 30 cm. or less 
long, petiolate or subpetiolate .. . a ¢ aa oe 
Spur vesicular, longer than lip; median aes of lip 
reflexed; disc in front of callus inormate . . . O. quadriloba 
. Spur cylindrical, shorter than lip; median lobe of 
lip not reflexed; disc in front of callus 3-carinate . . . . 16 
Pseudobulbs 2-leaved ; leaves subpetiolate, 20-30 
cm. long; inflorescence racemose; lateral lobes of 
lip rounded, larger than median lobe . . . . O. sclerophylla 
Pseudobulbs 1-leaved; leaves petiolate, less than 
15 cm. long; inflorescence branched ; lateral lobes 
of lip subquadrate with obtuse angles, equal to, or 
somewhat smaller than median lobe . . . . QO. analavelensis 
Plants caespitose ; pseudobulbs aggregate, ecol- 
liferous or with hardly any projections; leaves 
sessile or with conduplicate, short, petiole-like 
base ... ‘ ee eo hie 2 ow ee ole 
Plants diicsdutouxt : spendouaihe ners. 
prominently colliferous, leaves distinctly petiolate . . . . 25 
Pseudobulbs 2-leaved . ......... ++ 4. 419 
Pseudobulbs l-leaved . . . . 1... 1 ee ee ee ee 20 
Inflorescence profusely paniculate; lateral lobes of 
lip faleate, when expanded parallel with, and as long 
as midlobe; midlobe of lip wider than long; spur 
conical, acuminate ..... . 2. ee «OJ gracillima 
Inflorescence racemose or rarely with one or few 
short branches; lateral lobes of lip triangular to 
oblong, when expanded rectangular with midlobe ; 
midlobe of lip as wide as long, subquadrate; spur 
vesicular, obtuse. . . . .-. . . +. . . QO. roseovariegata 
Leaves ovate, subcordate at base... ....... + 21 
Leaves elliptic to oblong-elliptic, cuneate at base . . . . 22 
Sepals and petals similar, elliptic to ovate-elliptic, 
obtuse; lateral lobes of lip much larger than mid- 
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