petals. Both of these collections appear to consist of more 
mature plants than the typical number. 
Pleurothallis pertenuis appears to be very close to 
the Costa Rican P.vittarifolia Schitr., but differs in its 
glabrous sepals. It is dissimilar to P. uniflora Lindl. in 
its much shorter stems, smaller leaves and deeply biden- 
tate lamina of the lateral sepals. It is apparently allied 
to P.hymenantha Lind|., but has shorter stems and dis- 
similar shorter petals. 
Britisu Guiana, Essequibo River, Moraballi Creek, near Bartica. 
Nearly at sea-level. ‘““Minute epiphyte. Fl. brownish orange in bud.”’ 
September 15, 1929. N. Y.Sandwith 304 (Tyre in Herb. Kew.) : Aru- 
ka. June 1897. E.F. im Thurn 84: B.-B. | Barima-Barama | Road. No- 
vember 1896. im Thurn 84: Roriabo. “'7. XI. 94. Fl. deep orange.”’ 
im Thurn 84: Pomeroon River. March 1884. George Jenman 1996 (All 
in Herb. Kew.) 
Octomeria erosilabia C. Schweinfurth sp. nov. 
Herba rigida, crassa. Rhizoma repens. Caules pau- 
clarticulati. Folia erecta, oblongo-linearia vel lineari-ellip- 
tica, valde coriacea, acuta, breviter petiolata. Inflorescen- 
tine dense glomeratae : flores numerosi. Sepala lanceolata, 
acuminata. Petala similia, ovato-lanceolata. Iabellum 
prope basim trilobatum; lobi laterales parvi, auriculi- 
formes; lobus medius multo major, ovato-oblongus, 
marginibus erosis; discus bicarinatus. 
Plant rigid, stout. Rhizome creeping, stout, woody, 
concealed by the imbricating fibres of sheaths. Roots 
tibrous, glabrous, branching, numerous. Stems erect or 
ascending from a decumbent base, about 9-16 em. long, 
monophyllous, 3- to 4-jointed, mostly concealed by close 
cylindrical evanescent sheaths, longitudinally sulcate and 
4-angled in the dried specimen, about 1 em. apart on the 
rhizome. Leaves oblong-linear or linear-elliptic, rigidly 
erect, shortly but distinctly petioled; blades 9 to about 
17 cm. long (the longest blade incomplete), about 1 cm. 
[ 85 | 
