CENTRAL AMERICAN ORCHIDS 
productum, antice triangulari-subacutum. Unguis labelli 
gracilis, membranaceus. Discus prope unguem callo per- 
magno instructus. Columna gracilis, minute glandulosa, 
antice supra unguem labelli prominens. 
Roots fibrous, whitish, smooth. Secondary stems 
about 12 cm. long, conspicuously two-winged above, clothed 
with four tubular closely oppressed sheaths, the uppermost 
3.5 cm. long, brownish when dry. Leaf 7 cm. long, about 
2 cm. wide near the middle, oblong-lanceolate, acuminate, 
acute, coriaceous, shortly conduplicate at base. Peduncle 
slender, about 3.5 cm. long, with a tubular bract near the 
middle, 1-fIowered. Lateral sepals about 1 cm. long, 
coherent nearly to the apex, forming a narrowly elliptical 
lamina which is 3 mm. wide near the middle and shortly 
bidentate at the tip. Dorsal sepal similar, 1 cm. long, 
acute, 3-nerved, the nerves prominent on the inner surface. 
Petals 8.5 mm. long, hardly 1 mm. wide, linear-falcate, 
acute, thickened on the anterior margin, minutely glandu- 
^ lose, contracted near the base to form a narrowly oblong claw 
which is heavily carinate along the middle on the outer sur¬ 
face. Labellum 2 mm. long from the point of insertion to 
the tip, when spread out suggestive of a ram’s head, the 
lateral lobes or auricles representing the horns, the triangular 
middle lobe representing the head; lateral lobes 2 mm. 
long, probably porrect, narrow, acute, glandular-hairy; 
middle lobe hardly 1 mm. long, obtuse, densely glandular- 
hairy. Disc with a prominent callus in front of the claw 
and a thickened median nerve. Column 3 mm. long, 
densely puberulous, with a small projection in front near 
the base. 
Closely allied to Pleurofhallis arietina Ames, from 
which it is readily distinguished by means of the flattened 
petals which are only thickened on the anterior margin 
and not at all triquetrous. Vegetatively it is a smaller 
plant. 
Mexico, State of Chiapas, Chicharras, E. W. Nelson 
3763, February 6, 1896. 3000-6000 feet altitude. (Type 
in Herb. Ames No. 7885.) 
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