VOL. XIX PP. 143-154 SEPTEMBER 25, 1906 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



DESCRIPTIONS OF NEW SPECIES OF ACORIDIUM 

 FROM THE PHILIPPINES.* 



BY OAKES AMES. 



The following list of new orchids is based on recent collec 

 tions made in the Philippine Islands. I have divided the 

 species into two sections, designating as Euacoridium all those 

 species which lack lateral arms of the column, and designat 

 ing as Platydinis all those which have such arms. The 

 former section is represented in the Philippines by more species 

 than the latter and is based on Acoridium tenellum, Nees & 

 Meyen. Unless otherwise specified, the type specimens are in 

 the herbarium of the Bureau of Science, Manila, and duplicate 

 types are in my own herbarium . They will all be illustrated in 

 the serial Orchidaceae, issuing from the Ames Botanical Labor 

 atory. 



\ 1. EUACORIDIUM. 



Acoridium Williamsii sp. nov. 



Pseudobulbicaespitosi,fusiformes; folia Hnearia, setaceotriangularia ; pe- 

 dunculi quam foliis breviores ; flores distichi; sepala lateralia ovato-lan- 

 ceolata, acuta, 3-nervia; petala rhombiformi-oblanceolata, acuta, 3-nervia; 

 labellum 3-callosum, 3-lobatum, lobis lateralibus oblongo-falcatis, obtusis, 

 lobo medio oblongo obtuso. 



Grass- or rush-like tufted plants, in habit very similar to A. tenellum, 

 Nees & Meyen. Pseudobulbs approximate, clustered, fusiform, 7.5 cm. 

 long, tapering from a slender base. Sheaths elongated, tubular, maculate, 

 acute, closely appressed to the pseudobulb. Leaf linear, triangular in cross 

 section, 25 cm. long, about 1 mm. thick, acute. Peduncle filamentous, 

 somewhat shorter than the leaf, from near the summit of which it appears 

 to arise, being for the most part enclosed by it. Inflorescence slender, 

 about 7 cm. long, 5 mm. through. Bracts glumaceous, longer than the 

 ovary, 2 mm. long. Flowers 2-3 mm. apart, in 2 rows, greenish-white, 

 forming a graceful pendulous raceme. Lateral sepals ovate-lanceolate, 

 acute, 3-nerved, 3 mm. long, 1.5 mm. wide. Upper sepal narrower, oblong, 

 3 mm. long, 1 mm. wide. Petals rhombic-oblanceolate, acute, 3-nerved, 

 about 3 mm. long, 1 mm. wide. Lip 3-lobed or trifid ; lateral divisions 

 * Contributions from the Ames Botanical Laboratory, No. 5. 



30 PROC. BIOL. Soc. WASH., VOL. XIX, 1906. ' (143) 



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