lip quadrate, truncate; midlobe of lip with a 
rectangularly transverse, erose apex . . . . . QO. erosilabium 
20a. Petals without transverse bars; lateral lobes 
of lip rounded; midlobe of lip 2-lobulate 
without an erose apex oo a oe ey -21 
21. Pseudobulbs one-leaved ; lip wider than long, 
transversely elliptic in outline . . . . . . O. chimborazoénse 
21a. Pseudobulbs two-leaved ; lip as long as wide, 
rhombic in outline . 2... . . . . . . . OF. tunguraguense 
SYSTEMATICS OF SPECIES 
Oncidium olivaceum H.B.K., Nov. Gen. et Sp. PI. 
1: 847, 1816. 
Syn. : Oneidium cucullatum subvar. olivaceum (H.B.K.) 
Veitch, Man. Orch. PI. pt. 8: 31, 1892. 
Oncidium cucullatum var. olivaceum (H.B.1K.) Gower 
in Garden 55: 88, 1899. 
Type: Colombia, Depto. de Cauca, Puracé near Pop- 
ayan. Coll. Humboldt no. 2020! (P). 
Observation: Dorsal sepal 16 mm. long, 6 mm. wide; lateral sepals 
cymbiform, bifid, 16 mm. long, 7 mm. wide; petals 15 mm. long, 8 
mm. wide; lip 3-lobed, lateral lobes obliquely ovate, 12 mm. long, 
7 mm. wide, midlobe from a narrow isthmus reniform, deeply cordate 
at base, bilobed in front, whole lip 30 mm. long, 32 mm. wide across 
midlobe. The callus is triangular laterally, keel-like, with a small, 
divaricately-spreading lobe, resembling nostrils on each side. 
Oncidium olivaceum is readily separable from O. cucullatum by its 
callus which is one-fourth to one-sixth of the length of the entire lip 
and by the presence of nostril-like lobes on each side of the nose-like 
keel, It is noteworthy that I have not seen any material of this spe- 
cies outside the Cauca area in Colombia. 
Oncidium olivaceum var. giganteum ( Hort.) Stacy, 
comb, nov. 
Basionym: Oncidium cucullatum var. giganteum Hort. 
in Garden 22: 166, 1882. 
Type: Reported only from cultivation; no specimen 
is known to exist. The original color plate is regarded 
here to represent the holotype. 
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