180 FIELDIANA: BOTANY, VOLUME 28 into a transverse peltate plate about 1.6 mm. across; mid-lobe minute, oblong-ovate, long-hirsute. Column about 1.4 mm. long, dilated above, orchid-rose (Fig. 31) Type in herb. Chi. Nat. Hist. Mus., no. 1207544, isotype in Herb. Ames no. 64841, on densely forested steep south-facing slopes overlying sandstone, between "Cave Rock" and base of high sandstone bluffs, Ptari-tepui' state of Bolivar, alt. 2100-2285 m., October 30, 1944, Julian A. Steyermark 59540 "leaves pale green above and paler green beneath". This species appears to be allied to Lepanthes cyanoptera Reichb. f., but has longer leaves and dissimilar sepals and petals. Pleurothallis callifera C. Schweinfurth, sp. nov. Herba epiphytica, mediocris, caespitosa. Caules numerosi, graciles, variabiles, apice unifoliati. Folia valde variabilia, saepissime horizontalia, lanceolata vel saepius ovato-lanceolata vel ovata, acuta vel acuminata, basi cordata. Inflorescentiae abbreviatae, uniflorae, singulae vel plures. Flores parvi, bilabiati, glabri. Sepalum dorsale oblongo-ovatum, concavum, acutum. Sepala lateralia in laminam triangulari-ovatam, acutam, concavam omnino connata. Petala patentia, lineari-lanceolata, acuminata, basi obliqua. Labellum in positu natural! arcuato-recurvum et sulcatum, expansum rhombico-ovatum, membranaceum; discus prope basim carina transversa crescentiformi ornatus. Columna crassa, perbrevis. Plant epiphytic, medium-sized, caespitose. Roots numerous, fibrous, glabrous. Rhizome abbreviated. Stems approximate, slender, provided below with 2 close separated tubular sheaths of which the upper is much the longer, very variable in size, about 9-23.5 cm. long, 1-leaved at the apex. Leaf very variable in form and size, commonly horizontal or widely spreading, lanceolate (rarely) to ovate-lanceolate or ovate, acute or acuminate with a minutely tridenticulate tip, cordate at the sessile base, 5.8-10.8 cm. long, 1.9- 4.4 cm. wide. Inflorescences abbreviated, axillary, 1-flowered, apparently solitary to several, enclosed in an evanescent conduplicate spathe. Flower small, glabrous, bilabiate. Dorsal sepal oblong-ovate, acute, 3-nerved, concave, about 7 mm. long and 4 mm. wide. Lateral sepals entirely connate into a triangular-ovate concave lamina which is acute, 5- to 6-nerved, about 7 mm. long and 4.4 mm. wide. Petals linear-lanceolate, acuminate, oblique at the base, 1 -nerved, about 6 mm. long and 1.1 mm. wide at the base. Lip arcuate-recurved and sulcate in natural position, rhombic-ovate when expanded, submembranaceous, cuneate below, obtuse at the apex, 3-nerved with the mid-nerve clavate and thickened near the tip, about 4 mm. long and 3.2 mm. or more wide when expanded; disc with a prominent transverse crecentiform keel or callus near the base. Column abbreviated, stout (Fig. 32). Type in herb. Chi. Nat. Hist. Mus., no. 1206418, isotype in Herb. Ames no. 64844, on densely forested steep south-facing slopes over-
BOTANICAL EXPLORATION IN VENEZUELA - I 181 FIGURE 31 Lepanthes exilis. 1, Plant (X 3/5); 2, Flower, from the front, (X 7); 3, Petal (X 14); 4, Lip (X 14).