the two pairs of keels on either side of the center are low 
and undulate running nearly to the apex of the lamina; 
the central keel appears to originate near the anterior 
third of the disc and, increasing in height, to extend as an 
undulate ridge nearly to the apex. Column very slender, 
arcuate, about 3.1 cm. long, dilated above, with a pair of 
triangular-lanceolate arms. 
Another collection (Manuel Valerio 2412) is refer- 
able to this species. However, it is rather more slender 
than the type. Its leaves are slightly longer and narrower, 
up to 26 cm. long and 7 cm. wide. Its flowers are rather 
smaller, the sepals, petals and lip being about 38.5-3.8 
cm. long and the outer keels on the dise of the lip are 
reduced in size. 
Sobralia undatocarinata appears to be related to S.lu- 
teola Rolfe from which it differs in having ecarinate lat- 
eral sepals and in the lip lacking fimbriate-pilose nerves. 
Costa Rica: La Estrella de Cartago, ‘‘Flor blanca con el labelo 
listado de purpura. ... Comprada aun campesino’’, August 22, 1933, 
A.M. Brenes 206 (Tyrer in Herb. Ames No. 46367); La Palma, at 
1500 meters altitude, ‘Flor blanca, lustrosa, con el centro interior 
del petalo central lila morado-Una o mas flores en cada inflorencencia- 
Florece en agosto y setiembre-Confinada a determinada zona en La 
Palma-Epifita o terrestre-’’, August 16, 1937, Manuel Valerio 2412. 
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