CENTRAL AMERICAN ORCHIDS 
acutum, obscure trilobatum, supra medium valde deflexum. 
Columna ebrachiata. 
Epiphytic herb up to 44 cm. tall. Secondary stems 
about 3 mm. in diameter in dried specimens, monophyllous. 
Leaf 16 cm. long, 5.3 cm. wide, narrowly lanceolate or 
elliptic-lanceolate, contracted at base into an elongated sul- 
cate petiole which is about 2.5 cm. long. Flowers in a dense 
cluster near the base of the petiole, glomerate, spreading on 
slender pedicels, yellowish. Pedicels with the ovary about 
9 mm. long, very slender, sheathed by an ample hyaline 
bract near the base. Lateral sepals 8-9 mm. long, united 
to the tip, forming a linear 4-nerved lamina which has in¬ 
volute margins. Dorsal sepal 8 mm. long, 2.5 mm. wide 
below the middle, strongly concave at the base, lanceolate, 
acuminate, 3-nerved, the nerves prominent on the exterior 
surface. Petals 7 mm. long, up to 1 mm. wide, linear, 
tapering gradually to the acute tip, 3-nerved. Labellum 
fleshy, 2 mm. long, hardly 2 mm. wide at the base, ovate in 
outline, obscurely 3-lobed; lateral lobes rounded; middle 
lobe 1 mm. long, triangular, acute, 3-nerved. Column 
about 1 mm. long, simple. 
Similar in habit to Pleurothallis ruscifolia R. Br., but 
larger throughout, with a 3-lobed labellum. From P. ventri- 
cosa Lindl., which it resembles in general aspect, it differs 
conspicuously in the structure of the labellum. 
Costa Rica, Cachi, C. H. Lankester 357. (Type in 
Herb. Kew.) 
Pleurothallis Nelsonii Ames sp. nov. Radices fi- 
bratae, albidae. Caules secundarii elongati, superne valde 
alati, complanati, vaginis quattuor instruct!. Vaginae 
caulis secundarii tubulatae, elongatae, in sicco brunneae. 
Folium anguste oblongo-lanceolatum, acuminatum, acutum. 
Pedunculus filiformis, uniflorus. Sepala lateralia paene 
usque ad apicem cohaerentia, laminam ligulatam forman- 
tia. Sepalum dorsale simile. Petala linearia, acuta, minute 
glandulosa, prope apicem incrassata, prope basim in 
unguem carinatum contracta. Labellum unguiculatum, 
valde glanduloso-pubescens, in auriculas lineari-triangulares 
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