Tas. 6471, 
PACHYSTOMA? Txomsonranum. 
Native of Western Tropical Africa. 
Nat. Ord. OrcutpEm.—Tribe EprpEenprex P 
Genus Pacnystoma? Blume ; (Reichb. f. in Walp. Ann. vi. 462.) 
Pacuystoma? Thomsonianum ; rhizomate elongato, pseudobulbis depressis orbicu- 
latis tunicatis 1-foliatis, folio anguste elliptico-lanceolato utrinque acuminato 
membranaceo plicato, pedunculis a basi pseudobulbi ascendentibus folio brevi- 
oribus gracilibus pubescentibus 2-floris, spathis 1 v. 2 ovato-lanceolatis, bracteis 
spathaceis subacutis ovario brevioribus, perianthio explanato, sepalis albis, dor- 
sali majore erecto oblongo-lanceolato acuminato marginibus infra medium 
recurvis, 2 lateralibus patenti-decurvis elongato-lanceolatis acuminatis apicibus 
recurvis, petalis albis horizontaliter patentibus sepalis lateralibus squilongis 
acuminatis, labelli lobis lateralibus erectis subquadratis carnosis cochleatis intus 
rubro striolatis intermedio elongato triangulari in caudam elongatam sensim 
producto rubro-striato, columna suberecta apice rotundato, anthera deflexa 
cuneato-lanceolata, polliniis 8 parvis caudiculis elongatis connatis, glandula 
parva trigona. 
P. Thomsonianum, Reichb. f. in Gard. Chron. 1879, ii. 582. 
I am quite unable to refer this beautiful little plant to any 
other described genus of Orchids than that in which Prof. 
Reichenbach has placed it, and shall leave it for Mr. 
Bentham to settle its position as he elaborates the genera 
of Orchidew for the “Genera Plantarum,” a work upon 
which he is now engaged. Neither in habit nor in floral 
characters does it appear to me to accord with Pachystoma; 
and if the figure of the pollinia here given is correct, and I 
_have no reason to doubt this (having supervised the artist 
when making the drawing and its analyses), it must be re- 
ferred to the Tribe Vandew, as now accepted, and not to the 
Epidendree, to which the described species of Pachystoma 
truly belong. I think, however, it is a question how far the 
presence or absence of the so-called gland is of itself a safe 
ground on which to divide the Hpidendree from the Vandee, 
more especially when it is considered that this appendage to 
the base of the pollen masses is formed of a portion of the 
column (the rostellum) that varies greatly in its nature and 
extent in different genera, so that Mr. Darwin remarks, that 
“the differences in the shape and size of the removed por- 
JANUARY Ist, 1880, 
